Colemak is, far as I know, unbeaten when it comes to shortcuts, surpassing even QWERTY. That's mattered less to me since learning and creating vim-like configs, but is still useful when those are unavailable.
Norman's big disadvantage is its very high same finger ratio. On the blog, he suggests this is by design:
the Norman right index and middle fingers are overloaded compared to the other modern layouts which negated any of the improvement the other layouts strived for. Norman tries to assign common characters to strong fingers and I think those are my two most agile, strong fingers.
Same finger, however, is a very important metric (definitely in speed, arguably in comfort), so I'm not sure that's worth it.
To address the rest of your list:
Comfort: As davkol points out, what people are comfortable with can vary. Some people like rolls (which colemak has a lot of) more than hand alternation (which colemak has little of) and vice versa. Unfortunately, there haven't been serious medical studies like "rate of RSI by layout" (you can blame QWERTY's dominance; there'd be little point in finding out regardless of results), so those kinds of questions can't be definitively answered.
Learning speed: if you're a QWERTY touchtypist, tarmak is probably the best transition method, period.
Last edited by lalop (10-Jan-2014 14:25:18)