i'm not really a glock fan--though i've used them alot over the past 23 years--the goal is to become very proficient with most of the different systems.
early on, i tried some of the various modifications, and found that i almost always liked the rigs "as is" from the factory. this led me to the concept of basically trying to
adapt myself to the rig--to learn to work with the different types of rigs as "near close to stock as possible", to make myself more versatile.
as far as the concept of .22 rf kits for rigs--in my mind this is not the best idea, as the recoils levels are vastly different, and with that in mind, i feel it is best to work on basic general skills with an actual .22 rf firearm, getting valuable trigger time--as you work to improve overall basic skillsets. its important to me to have an essentially different rig in hand when firing .22 lr, so our mind does not get "fooled" when we go back and grip the very same gun and experience full recoil with carry loads--the .22 should feel and recoil much differently--because it is--as we train ourselves in those basic, or general marksmanship techniques.
for basic skills training with a .22 rf--whether looking to improve sight acquisition time, sight picture, grip, trigger control, speed in presentation and engagement, etc., etc., its all about "training the cortex", as bruce lee used to say (if i recall his words correctly).
work on all of the basic essential skills with an actual .22 rf pistol--i will often do sessions of 350-500 rounds every 10 days or so--at times more, and usually never less. occasionaly, i will follow these up with carry loads in a carry piece "to keep the feel" and the contrast, of the carry gun in full recoil. another point to consider is that these conversions kits will run you nearly as much as a decent .22 rf pistol.
its great to be able to adapt and use different systems, but i think we need to "stop with that idea" when it comes to how the loads will actually recoil in the specific rigs that we will carry for self defense--they shouldn't act or feel like they are stoked with a squib loads (22 rf) while in actuality the rig in our hands at the moment of need is actually a full power 40 s&w with its attending recoil.
i chose to make a clear line of demarcation there--but this works for me--you've got to test, try, experiment to find what works for you, and implement that strategy...
as a point of interest regarding stock or near stock rigs, here is a video with l.e.o. marshall luton shooting a glock 17, that is very close to "pure stock" (only part that is not stock--the gun has a 3.5 lb. connector):
http://www.youtube.com/watch?v=JbC5mEc6ipE