I'm also not a fan of heavy ring-finger use - not just period/full-stop, but also Y (and W) as well - but maybe I just have weaker than average ring fingers! Combinations that involve ring-finger with pinky are especially less than ideal, e.g. WA, YO.

That said, ring-finger-bottom-row still beats index-finger-middle-column in my mind.

I don't think I would be willing to take an action regarding it.

(If alphabets only had about 16 letters it would be perfect!)

IMO position of period is not ideal, but it is good enough. One of the goals of Colemak was to keep shortcuts and non-letters in their qwerty places, that does not sound like a benefit for creating more optimal layout, but in fact the result is happened to be quite good and optimal. As we all know, it is hard to create ideal layout with existing limitation for keys placement in standard (and even non-standard) keyboard. Moving something inevitably cause to move something else, and the final result that will not be Colemak any more. Workman is example for that :)

Looking at those character frequencies, the elephant in the room (for coding) is not period/comma, but the parentheses (), which are on awkward shifted positions.

In the past I considered row-swapping [] and -= keys, but maybe it's more beneficial to swap () and [] (the characters, not the whole keys).

I don't see how this approach can be better than simply having a dedicated symbols layer containing all your most common programming keys (brackets etc) on the home row.

Layers 3 and 4 are perfect for this unless you need them for foreign language symbols. But even then most languages don't have so many special symbols that you couldn't also make optimized layers for your own usage patterns. If you only type in English, this is an especially easy quick win.

@stevep99 I would be quite keen to use a dedicated symbols layer and while I'm an avid Extend layer user (can't imagine life without it), I've never gotten around to setting up an AltGr layer. Maybe I've never quite understood how it works. I use Alt quite a lot (mostly in Excel) and I think I was worried how those combos would continue to work.

I use a modifier setup like in the following (with the difference that I've got Ctrl mapped to the Shift keys) so AltGr combos should still be easy enough to reach.

That said, I'm finding the [ ( { } ) ]  keys on the number row pretty easy to reach with my setup so I'm not sure that will be such a big requirement anymore for me. Numbers and dates have become quite an annoyance now though so what I would like is a good Numpad layer. Something that also sets numbers apart from punctuation and symbols is that number digits tend to come in clusters so that could be optimised for whereas the other symbols tend to be more dispersed in the text and often come only one character at a time.

Thanks DreymaR, looks great. Is there a way to have it activated as a toggle so that Ext+AltGr activates it and it stays active until deactivated with Ext+AltGr again?

Thanks. I wanted to try it out last night but I ran into some problems. I've been using a version pkl_eD.exe from about two years so I downloaded the latest EPKL.exe to try out the Extend2 Numpad layer. I used the standard Cmk-eD_ANS_CurlAngle layout but wasn't able to activate extend at all. I looked through the various .ini files to see if there were any settings to be enabled but it didn't look like it to me.

I suspect this might be due to me having remapped my modifier keys with SharpKeys at the registry level. In particular I have Capslock mapped to the LAlt key so perhaps that's why it's not registering it? I use SharpKeys because modifier key mappings didn't use to work with pkl_eD but perhaps this is fixed now with EPKL so I don't need this anymore?

Sorry, I'm not sure if I expressed myself properly because I never know what the convention is but my LAlt key/button sends the Capslock signal. With pkl_eD that works fine with Capslock as the Extend key.

To test EPKL I just shut down pkl_eD and started EPKL but it doesn't seem to be working. The usual alphanumeric layer is coming through fine with EPKL though.

In Dvorak brackets are pushed to the top row so they are all up there near the bakspace.
It's a bit fuzzy up there.  Like I get my 5 and 6s sometimes mixed, nice that they are grouped together, but still awkward.  That must have been the inspiration for programmers' Dvorak.  Where they are balanced between the hands.

Period gets prime placement on Dvorak.  Probably a very good spot.  But I too struggle with copying texts, not so much from the periods, but because of the shifting required for the next character.  That's far more of a slow down.  In the past I tried sticky keys, which felt promising, but I didn't stick with.

That's not to say that the period placement isn't a problem for you.  Auto captilisation on touch devices gets around the shifting irritation.  Though that can also be an irritation!