Similarity to QWERTY is not a disadvantage I believe, unless you're like you and me and come via Dvorak (or another radically remapping layout).

I don't believe in the hypothesis that more different layouts (or languages) are easier to hold in your mind. You just need to sort them out, and from then on similarity will be beneficial. However, while learning Italian I've taken care not to train Spanish or Portuguese at the same time – so I chose to polish my German a little precisely because it's more different from Italian than the other latin languages. Keep in mind though, that this is in the learning/training situation not in real usage!

There is a high price to pay for learning Dvorak. First when you learn it, then if you're curious and cheeky enough to leave it you pay a high price again. I did, and you do now. Best of luck with your endeavours! :-)

My theory - I am looking for data that confirms this OR that denies it, if you know of any studies, please post them - OK so here it goes:

My theory is that " rolling layouts"  such as Colemak are easier to learn than "alternating layouts" such as Dvorak. Because "patterns" on one hand are easier to remember than patterns on two hands.

Reading some of your comments on my own threads as well, you clearly hate Dvorak; probably more than the amount you dislike QWERTY. :P

I would agree to DreymaR, in the QWERTY world it is easier to learn Colemak than Dvorak. I have my own story of unsuccessful attempt of studying Dvorak. May be I was not motivated enough that time, but Colemak went much easier later on.

I too found Dvorak pleasant to type on, except for a few quirks. Shortcuts were annoying, especially W and V next to each other (so I'd close a window when trying to paste). And the Norwegian letters were awkwardly placed; if I had had the WideAngle mod at that time however, that wouldn't have been an issue.

I'd been typing Dvorak for about 18 years previously (all the while staying "bi-lingual", basically having dvorak at home and qwerty at work. I felt rather proud of that ability to be honest), but switching from Dvorak turns that on its head.  It was a bit of an uphill climb (I've been doing Colemak for the last 5 months).

The "hump" was the first  week, when I basically just hunted and pecked.  It was rough.

The good news is that I'm up to a reliable 55 wpm.  The entire reason I switched, to be honest, was to get the shortcuts back. (and that closing a window thing.. my god that pissed me off so much) I got tired of remapping the keys (because even though you can do copy/paste with the right hand, I got tired of taking my hand off the mouse.

Admittedly, I most dislike the loss of typing periods and commas with my left pinky and ring finger.. I'd rather stretch than curl, which is what you have to do with qwerty and colemak

I can't say that I "love" colemak.  there is much to miss about Dvorak, but not the shortcuts. 

After I get completely up to speed on colemak, I may have Unicomp make me a Colemak keyboard with Q,W & F switched with ' , & . , just the way my brain likes it.  :D

Yes, the shortcuts are a lot better on Colemak. OK.. CTRL + Z/X/C/V looks like a recipe for disaster for your fingers. But it is manageable as compared with the using it on Dvorak. In addition, if you are on Mac OS like I am, usage of Cmd + ZXCV is far more easier and simpler. I can use my thumb on Cmd and that leaves my four fingers on my left hand free to press whatever key they please.
On Colemak, this becomes even more useful. In addition to the standard ZXCV, you have A/S/T/W/Q/P... Colemak is the "keyboard shortcut king" of layouts. Can't get that with Dvorak.

My two main reasons for switching over to QWERTY now is
1. I wanted to be able to touch-type on any computer.
2. On Colemak, I started to feel pain after typing for long hours. The slight dull pain was on my forearm on my right hand and on my fingers. The fingers felt really tired. I never felt that when I was using Dvorak. This part had me a bit confused as most reports stated that on Colemak, my fingers were supposed to be doing less travel and work.

If anyone wants to choose an alternative layout, I would suggest that they try out Colemak first before they choose anything else. If they feel comfortable on it, great. If not, then please go with Dvorak.

As for me, QWERTY is no picnic, but at least I know that the fatigue is due to the fact of more effort being used for typing. if I was to choose an alternative layout for myself, I would probably go with Dvorak. I loose the shortcuts, but it was the most easiest & the most comfortable for me.

Completely agree with you there.

I understand that there is some kind of pain will be there when learning new muscle memory. But the pain that I am talking about was not something I felt initially. This pain came after using Colemak cold turkey for 2 years.

Regarding point 1... The usage of outside terminals is rare and brief at best. I do not think that it is worth changing the layout if I am going to be using the system of a period of 10 - 15 mins. Saves me time if I do not have to. At the same time, I do not want to be stuck using a hunt and peck method; just because my fingers are used to an alternative layout.
Perhaps it is a defeatist idea, but I guess if you can't beat QWERTY....

Regarding point 2, I used Dvorak for about 6 - 8 months before I went completely cold turkey with Colemak.
My experience with Dvorak was good. For instance. The 'l' problem, sorted it out in the same way that I type P on QWERTY - I use my Right Ring finger. Even use the same finger for the Backspace button. Its a muscle memory I am glad that I still have since I make mistakes all the time.
When I was using Dvorak, I was amazed at how fast I managed to learn the layout, even though the only point of reference was on a cheat card I had in front of me. My keycaps still remained as QWERTY. After two weeks, I did not make as many mistakes as I did with Colemak and keep doing with QWERTY now.
The movement felt a bit more fluid and natural. Not everyone is the same, that is why I would always suggest to someone to try out Colemak first before trying Dvorak.

Well, if "learn a layout" is akin to "learn the guitar" by learning where to place your fingers in three grips. It won't be good music in an afternoon, for most. ;-)

Are you saying that you regret switching to Dvorak? Would you have switched to Colemak if you had the chance?

AR and OI aren't the best; RA and OI may be even worse. But I think that August Dvorak in general was too negative of rolls. As you say, he was discussing typewriters with heavier actuations. And if you try typing oienoenoienoien vs oaoaoaoaoaoao for instance, you feel how rolls can be nice (although it's certainly an extreme example!). Again, I think the best may be frequent alternation and small rolls in combination.

Inward rolls are often very comfortable, even when spanning rows. Examples: oun aft yun wft vsr afp, and so on. Good trigrams make for very nice flow!