Being able to type on a peer or customer's machine, without struggling with QWERTY vs Colemak is definitely worth something. The problems you solve get more difficult and abstract, so you are writing more difficult but less code.

The big exception that I can think of is that RSI can really put you out of action, so some adjustments or investment in that area can pay off. I have a Kinesis Advantage2 that fits in this category. It took some time to get used to, and it definitely slows you down on every other keyboard once you are used to it, but I find the ergonomics to be worthwhile, even if I retain the QWERTY layout.

The reality is the benefits you get from switching keyboard layouts is marginal at best.

The real benefits (in terms of RSI) come from things like a split keyboard or other modifications. Once I switched to a split (and tented, but I did both at once) keyboard I have had zero issues with any RSI.

The other big benefit comes from modifying the placement of modifier keys if you are a heavy keyboard shortcut person. I am, as an Emacs user, but for me it was “Emacs wrist.” I’ve had no problems at all after moving Alt and Ctrl to my thumbs with the split keyboard.