I was in similar situation few months back. I was choosing "normal" lens for my camera. I was considering two lenses you are mentioning and DA40. Which is somewhere in between in terms of focal length but another stop slower. On the other side it's beautifly sharp edge to edge straight from f2.8, and it's CA/PF are better controlled then on the FA lenses (at least the two we're talking about here). At the end I went with DA40, knowing FA35 will be not wide enough (DA40 leaves space for somthing like 28 or 30 (FA31ltd if I'll get seriously rich)) and FA50 was tad too long for my liking. Since then the little pancake lives on my camera as my primary lens, and it delivers great shots again and again. Of course my LBA didn't go away for too long, so couple of months down the line I managed to get F50 f1.7. If I can, I take both of them with 40 being on camera and 50 for really low light, some portraits etc.
Now I'm still after something to fill the gap between my Sigma 10-20 and DA40 (as gap stop measure I got Tokina 28 f2.8, but I'm really after AF lens, or very good manual).
so my conclusion, good luck choosing, but I think it doesn't matter because sooner or later you'll get both (and many more...)
BR