I use the Hornady XTP's as well, and I have noticed pressure signs well before where I do with a .429... now that being said, it doesn't keep me from using them...

as far as the "one molecule thick" lubricant, I think all you're going to do is smear it off in the forcing cone anyway.. and, if any surface is smooth enough to support a one-molecule finish, you're going to have trouble holding onto the object... be like trying to hold smoke..