Getting off track here folks! I know people use 50/1.4 lenses on film for portraits, so the 35mm is definitely a portrait capable length on APS-C.
Here are some shots from my 35/2 SMC Tak:
Mid-length
Head-shots
Full Body
Groups
Bust distance
There were all shot on a camping trip where I had ONLY the 35mm lens to do all my photography. Very versatile, but I never shoot above f2.8 with this lens due to blooming highlights at f2.
So to go back to the question...how valuable is having a 35mm at f2 or f1.4 for portraits versus the f2.8 I have been using on my tak or the upper limit of the DA35?