Warwick, a lot of guys I know have used Power pro without any problems whatsoever. I remember a post from a few months back about the South Africans havng problems with the Power Pro there but that is the only time I have heard of any issues with it.
All of that said, if you're buying a reel with it already loaded, I'll assume the line is used. If you're going on a trip to a remote location, I think that it is worth the expense of changing the line. It's just false economy to go out there without a fresh batch of line when you may not know much about how much use that spool of Power pro may have seen.
There would be nothing worse than getting out there and finding problems with it.