My observations on glues and chunks:

Many brands like Jaco and apparently the new TRC's have gone to CA. This makes for a very strong bond so no problems there but there is another issue. With the softer rubbers like yellow, pink, magenta, etc., the CA soaks into the foam a bit and makes it very brittle. The foam can actually tear right at the transition from foam with no CA in it and where the CA has soaked in. What you end up with is a torn edge but you still see foam on the wheel. This doesn't seem to be as much a problem with the harder rubbers like purple, black, lilac, etc.

Many other brands like CRC, BSR, etc. still use some sort of contact or rubber cement. When done right, I believe this is better as it does not make the foam brittle. The only problems is that if it isn't applied liberally enough, you can easily have a thin spot and if it is near the edge, it will chunk easily. If this happens, there will be little or no rubber left on the wheel. Also it can be weakened by some traction compounds.

So like everything else, it's a compromise.