I'm not familiar with what's on the market now. I used to use the Forcelle and Clark copper gaskets on drag race engines, with stainless steel "o-rings". As mark said you have to machine the block (cut grooves in it around the bores) to accept the rings, and the rings were made from stainless steel wire custom fit to the block's grooves. On the drag race engines, we didn't run any pressure on the cooling system. I never had a problem with water leaks, but the engines were torn down often and I can understand where there would be more risk of a water leak when a pressure cap is used, or when a higher than normal temperature is encountered.
There were three advantages to these gaskets for me. First is that the gaskets could be re-used after a tear down. I don't recall ever replacing one. Second is that I could select a gasket thickness that matched my deck height - handy if you changed pistons or something else in the rotating assembly. Third you could order the gaskets to exactly the correct bore size.
Do you need all this on anything but a race engine? No. In fact it's not a good choice for anything but one.
