If the OP rephrased his question to read, any "significant- worthwhile" benefit, then I still conclude no, as do several others who frequent this forum, the Search function is your friend.
In the other threads, the only "viable" upgrade route is the 4850 CF or the 4870X2 and this depends on budget and of course the resolution you game at, I want 19x12 with eye candy.
I have tried to choose my words carefully here, for clarification, by viable I mean cost vs noticeable improvement, this is completely different to stating the single 4870 512mb card will suffice.....if noticeable difference or improvement is what you are after than as I state, you only have 2 options.