I have both styles of the Kadet kits. The KadetII doesn't give much room for grabbing the slide, but it is very reliable.
The two differences between the two is that the SP-01 Kadet is a style more like the regular slides. They also come with three recoil springs to help accommodate different 22LR rounds, hotter vs weaker.
I have read that the Kadet II is supposedly more accurate than the SP-01, Shadow 2, P-07, P-09 Kadets but I haven't noticed a difference.
Good Luck