When comparing Colemak vs Workman, the Slant community recommends Colemak for most people. In the question“What are the best keyboard layouts for programming?” Colemak is ranked 3rd while Workman is ranked 13th. The most important reason people chose Colemak is:
If you rely on the Control-A/X/C/V shortcuts (select all, cut, copy, paste), these keys don't move from their QWERTY locations.
Question Ranking
Pros
Pro AZXCV don't move compared to QWERTY
If you rely on the Control-A/X/C/V shortcuts (select all, cut, copy, paste), these keys don't move from their QWERTY locations.
Pro Optimized for quick two-letter bigrams
Not only are the most common English letters on home row under your fingers, but many common two-letter combinations are placed next to each other as well allowing for a fluid "inward roll" motion of letter combos (a-r, r-s, s-t, n-e, e-i, and i-o combos). The inward roll motion is debatably speedier than optimizing finger alternation like Dvorak offers.
Pro Relatively quick to learn
If coming from QWERTY, only a couple of keys move between hands.
Pro Highly ergonomic
Pro Less lateral motion than Colemak
Colemak's focus on the home row is flawed. Due to differing finger lengths and the natural range of human hand motion, the center columns (even on the home row) take more effort to reach than the top row with the longer middle fingers. Workman takes this into account.
Pro Ctrl- AZXCV shortcuts are still accessible with one hand
AZX are in the QWERTY positions, and CV have only shifted one key right. This lets you use the mouse with the right hand and the shortcuts with the left, unlike Dvorak.
Pro Common English bigrams are optimized
This is an emphasis shared with Colemak, but Workman focuses on the easiest keys instead of the home row.
Pro Finger travel is very low overall
This is good for preventing RSI
Pro Good for programming
Common characters {} [] <> () / ' " are easily accessible by the right hand on the right of the keyboard.
Combinations ( { + } for example) are placed side by side on the keyboard which is useful as well.
Pro Most symbols and shortcuts are the same as QWERTY
Cons
Con Designed for English
Like Dvorak, this layout privileges English letter frequency, and lacks accented letters.
Since the topic is about programming, the argument is weak as most code is written in English, yet you don't want to learn a layout to type code, and another to type in your native language...
But the problem isn't specific to Colemak, it is tied to all "ergonomic" layouts, and might have no solution.
Con Bad for Vim users
Vim was designed on QWERTY. The HJKL "arrow" keys still kind of work in Dvorak, but their positions make less sense in Colemak.
Con The "HE" bigram is awkward
For all of Colemak's focus on optimizing English bigrams, the second-most used English bigram, "HE", is still kind of awkward due to same-hand lateral motion. This bigram is much easier in both QWERTY and Dvorak. If your concern is RSI, Colemak isn't good enough.
Con Designed to be used on a matrix style keyboard
This keyboard layout wan't designed to be used on a normal keyboard.