Home made MTF comparisons 50mm's, 35mm's, 28mm's and 100mm's + bonus 3.5/135 - PentaxForums.com
Scroll down a bit to see home made mtf comparing *my copies* of the two lenses. This doesn't compare absolute corners though.
Se also an earlier thread/post of mine
HD Pentax-FA 35mm F2 vs SMC Pentax-DA 35mm F2.4 AL on FF Pentax (K-1) - Page 2 - PentaxForums.com
In short my DA35 performs extremely well, arguably better in some respects, but it does show some degradation in extreme corners. Both in regards to sharpness and vignetting probably due to the smaller lens elements and the baffles. I have the newer HD FA version but differences should be minimal compared to the smc FA.
The FA35 can have a bit of a busy bokeh in challenging light such as back lit foilage but it often produces very nice bokeh. I haven't done side by side comparisons of more subjective qualities but no longer use the DA35 because the FA is slightly better over all.