Different STOL kits affect the airplanes in different ways. Some make for a better flying airplane, but some make for better performance at the expense of handling. The Robertson STOL kit, for example droops the ailerons and makes for much-improved short field work, but the ailerons become VERY heavy. I've experienced that on several different kinds of Cessnas, with similiar results. The good news is that when the STOL system isn't used, meaning the flaps are left up, the aileron control is normal. In the Robertson system, the ailerons both droop with the flaps, effectively creating full-length trailing edge flaps.
The heavy ailerons and restricted aileron travel and have been cited in a number of landing mishaps involving loss of control in a crosswind.
The difference between their use and not is displayed in the following video clips...the first with flaps up and the STOL system not in use:
http://home.comcast.net/~tcovey4/cleanstall.wmv
The second with the flaps drooped, and the STOL system in use. You can see the difference between the two in the stall propogation on top of the wing, as shown by the tufts:
http://home.comcast.net/~tcovey4/takeoffstall.wmv
You'll also notice the difference in the effort undertaken to recover, and how far the airplane departs, when the stall finally breaks in the STOL stall (second video). It does wonders until the wing finally pays off. If you happen to be close to the ground at that point without sufficient room to maneuver or recover, watch out.