Just to (eh hmm) break from the back-stap controversy for a moment - the stab-in wire junctions are in common use in a number of recessed can lights - they come already placed on the can wiring in the make-up box.
I've had zero problems with them in that particular application.
Removal is not so difficult, once you know the trick (this also works with old back-stabbed recepticles). The trick is to hold the wire firmly while twisting the device (recepticle or wire junction block) side to side and pulling (some force is needed). This sort of "unscrews" the wire from the lock-in tab. This also seems to retain the holding properties of the lock-in tab for re-use.
Stranded wire presents difficulties, unless it's tinned like the can light leads are.
I'm up for trying any device that saves time and presents no comprimise to the quality and longevity of my work.
