I have both of these lenses and although I do love my SMC K 24mm f2.8 lens - Sigma goes out for most part with K-01 - for simple convenience of AF. SMC K wins if it comes to film - no question about it. Both lenses will produce superb results - but SMC K is easier to set for hyper focal and snap shots away with everything sharp - sigma on the other hand allows a bit more selctive focus - with so close focusing ability also gives a chance to play with semi-macro shots. If it comes to rendering - I think SMC K produces warmer less clinically looking shots out of the box ( that's why it wins on film for me too ) - Sigma has more cold rendering and so requres more PP time to make the shot looks equally good. I don't have any examples at hand right now to compare these two in similar situations - but here are few snaps with Sigma AF 24mm f2.8 ( version II ) shot with my K-01 yesterday - with notes about PP.
>>-manntax-->
#1 - little PP here - some highlights / shadows touches with radial filter applied - little touch of vignetting added
#2 slight crop on the left side + some background blur added with brushes - originally everything in photo was in sharp focus; some vignetting added
#3 Some selective changes to tones of gree / yellow + little vignetting added
#4 no vignetting - lens is exposing uniformly at f5.6+, little barrel distortion ( +9 correction ), some highlights recovery, clarity applied
#5 some shadows + highlights recovery, touch of vignetting