Owning both, I can state that these are two completely different lenses.
The DA35 is about half the size and weight (by physical compare, not spec compare) of the FA31. The DA35 offers 1:1 macro that in spite of what some may tell you IS useful if you're into that sort of thing. And of course, the price for the DA35 is about half (or less) that of the FA31 (even used). Here is a closeup, from the DA35, no crop, full image.
The FA31Ltd on the other hand is more than a stop faster than the DA35. It's rendering (I think anyway) is better than that of the DA35. Not that the DA35 is Bad, far from it, but I do prefer the FA31. If you ever fancy using one of these on a film camera, the FA31 Is a film camera lens. The K7 focuses faster with the FA31 than the DA35 though the difference is minimal in my experience. Both are plenty fast for me. As to closeup capability, there is plenty of crop room with this lens.
All that aside, the bottom line is this.. Both will give you great results. Both took a little getting use to for me. As a general walk around lens though you probably wouldn't notice a Lot of difference in the results.
Pentax FA 31mm Limited - a set on Flickr Pentax DA35mm Limited - a set on Flickr
The 35 set covers the K20d and the K7. The 31 set covers the K10d, the K20d, and the K7. Check your private messages.