It might be more interesting than a 85/1.8, because it would be a dual role lens. Hmm...need to be persuaded to give up 60 macro.
The 60 has USM/FTM and internal focusing though, so that's what makes it special.
For $245 I wouldn't think twice. It's $390 new, shipped to my doorstep.
Hmm..
It's very interesting because the 90mm is particularly light, 405gm compared to 600gm for the 100 macro. This was one of my concerns, I want something small and light (because it will never travel alone, but rather with lots of other gear). The 60mm is 335gm. And performance as recorded by Photozone.de is superb.