I have to use copper on my big SOHC engine because the bore spacing is spread. A custom copper head gasket is the only way I can go. The engine only stays together for a few thousand miles before I tear it down, but I haven't had leak issues. Probably would though, if I tried to put 10K miles on them. One advantage to copper is that they transfer heat better than any other head gasket material. Leny, if you are running a lot of boost, that may be why you ended up with copper, to combat the heat. The other thing is the bore size, the thinner the area between adjacent bores, the more likely it is to blow a hole in the gasket due to heat. Copper wicks away the heat better than anything else. So if you have a really big bore in the block, and a minimum area between the bores, copper will be your friend.
If you're not on the ragged edge of boost or bore size, I'd agree than an MLS gasket would be a better choice - Jay