As for the 22 conversion kits, I'm not that impressed with them.
I would much rather have to seperate guns.
Have you ever shot a CZ with the Kadet Kit installed? CZ also make the Kadet as a dedicated .22 pistol, but most buy a 9MM CZ, and then add the Kadet Kit. Mine is just about as accurate as my Ruger MKII Target model. It is also very reliable with most bulk ammo.