For me a large part of the reason I use Vim and only Vim for writing code is it just makes the experience so much more enjoyable. I realise this is quite subjective, but my personal experience is that whenever I use a colleague's non-modal editor I find the experience frustrating even though I know how to use it. Years of using Vim has sensitised me to the constant annoyances that accompany using a conventional editor.

Has Vim sped up the rate at which I can edit text? Probably, but for me this is missing the point.

I'm not a physiotherapist but being able to rest my forearms/wrists on the table 99% of the time when using Vim significantly reduces the risk of RSI.