(xposted from /r/colemak)
A lot of people talk as if Colemak DH is a direct upgrade to vanilla. For some people the center column usage of DH in vanilla is a big problem, and DH is what works for them.
Obviously not saying DH is bad, in my case it just didn't work for me. I've been using some kind of Colemak 24/7 since February 2018, and I used DH fulltime for two months in that time period too. Here's some reasons I prefer vanilla:
1. All about the 'C' key
This was my biggest issue to overcome, although I completely learned the Colemak layout, I still always press 'C' with my index finger and learning to press it with my middle finger still had some strong mental resistance after 2 months, it just didn't feel natural to me. DH 'improves' the positions of D and H, but seemingly sacrifices the 'C' key by putting it where the almost never pressed X key is. The DH layout encourages you to press the D key with your index, similar to how you press C with your index on QWERTY/Colemak. If D and H was not a problem for you in the first place, the C key is now in a worse position, which for me killed my ability to use the layout.
2. Better shortcuts
I think ANSI is superior to ISO because the enter key is perfectly sized for touchtyping, compared to the fat enter key with ISO where you have to reach further to hit enter. The left shift is also bigger for gaming. Looking at the DH layout, Ctrl+Z is in the middle of the board making it harder to reach, and because Ctrl+D is next to Ctrl+C and V now, I seriously ended up bookmarking every other page I visited in Google Chrome.
3. Better vim keybindings
Just a nitpick. I don't rebind any keys when using Colemak with vim, and it's mostly totally fine. DH moves QWERTY/Colemak H to the QWERTY/Colemak M position, which makes already counterintuitive bindings slightly worse. I can imagine it's still totally usable.
These are ultimately small issues and DH is a great layout. I found these issues to be bigger than the benefits gained from the 'better' positions of the D and H keys (especially the 'C' key position), so I use vanilla Colemak over DH.
I made this post because I'm tired of people treating Vanilla like it's totally outclassed and DH is superior. If these issues don't affect you, and the placement of the DH keys is an issue for you on vanilla, I'm sure DH will provide improvement over the Vanilla layout. Every subsequent alternate keyboard layout that is an improvement from QWERTY suffers from diminishing returns, Colemak can only improve so much compared to Dvorak, DH improves even less compared to vanilla Colemak, after a while it does become academic.
But if we're rooting for our home team some more: Carpalx lists vanilla Colemak's effort rating as lower than DH. Whether DH is better in the first place is also dependant on which layout analyser is used etc.