Beings that Im the one that actually came up with that setup, I can answer most of your questions.
The sealer does dry but it remains pretty pliable. If you want something that dries a with less flexibility, I would recommend using the GE1200 sealant instead. One word of caution, tho, its very acidic so wear gloves if you use it because if it gets in your cuticles, it hurts for days. The sealant Jason sends out isnt acidic and works great.
In the beginning, I used the GM steel shim gaskets with this setup. They've been discontinued and mostly run out unless you get lucky and score some of them someone is sitting on them. The gaskets Jason designed to replace them seem to work well. I personally think double stacking them is still the way to go but thats neither here nor there.
Using the double GM steel shims, Ive only personally ever had two people blow the setup. Both times it took a large amount of boost to do it and it wasnt a simple pushing out of the gasket, the gasket exited the side of the block both times. Shane actually managed to blow both gaskets in half on his own car.
It's a tough setup.. as tough or tougher than anything else youre going to put on there. It's battle proven but like everything else, people that don't sell it will poo poo it.. there are a lot of good solutions out there these days.