Hylomar is pretty good stuff IMO. I thin-film gaskets with it and it performs well. I will still use RTV for the V.C. or cam cover gaskets on the "cover" side and Hylomar on the engine side, to be able to reuse the "old" gasket at least once, too. Laquer thinner is about the ONLY thing to dissolve it. It makes a teardown much easier than most other materials.
As to gasket material: If the tranny set is Payen, it's correct... what you're scraping off may be "ho-made" or an aftermarket set? I'd be leery of "thick" gaskets in a tranny as the case tol's are critical to bearing position/location in most instances.