I have the kenko AF, pic 6 here.
Kenko (?Promaster et al..) AF/Pz-AF 1.4x/1.5x Teleplus.... Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database
IQ is good IMO, I have used with adaptall 300mm and 200-500mm, and a bit with the DAL 55-300mm - Af still functioned. Should work well with a fast quality 70-200mm. There was a thread recently comparing some of these 1.4x tc's.
Camera model is fairly irrelevant in terms of operation and function I think - all those you mention will work the same. The ones with more MPx give you more cropping latitude - many would argue that you do as well/better simply cropping over using a tc.