I use the copper base and head gaskets exclusively on my builds as well, I like to be able to set my squish and port hight and know they won't move or change once torqued down and in service, The biggest advantage tho is that these can be reused over and over again. Right now I'm still buying mine from Juice and they alwas come to me well packaged and never bent. The base gaskets usually need a little trimming to match my transfers but that doesn't take any time at all during assembly.
My last build I wanted to use my old jug on a Dax Gen IV bottom end and the piston was too high so I made an aluminum shim at the base, double checked my timing and used a combination of a single .016 and .025" head gaskets which I glued together with a really thin coat of gasket shellac. I also use a very thin coat of shellac on the base gasket and shim for a perfect leak free seal everytime. The shellac holds up very well and when put on really thin there's no issues with squeeze out into your cylinder or case, absolutely no issues with even the smallest leaks, and disassembly is still nice and easy.
The use of shellac or sealants isn't needed at all if using a single gasket, but it doesn't hurt anything if used very sparingly.
Anytime you need to reuse one of these gaskets it's always a good idea to anneal the copper to ensure the best possible seal.