Endgame question

Generally speaking, what has the advantage during the endgame? Two rooks or a Rook, knight and bishop.

Assming a semi open position (aprox 1/2 the pawns gone)

I know that normally you would say that the side with the R+N+B is 1 Pawn equivelent up but I seem to remember a peice of research that possibly questioned this assumption for an at least partially open endgame.

Does anyone know a link for this research? It was into piece values and was posted on the forum some months back? It was a peice that re-evaluated and confirmed some of the long held beliefs of the relitive values of peices at different stages of the game using a large statistical sample for comparitive analysis.

reassess your chess is a awsome book....i think it talks about this with some real examples.....

they say what the plan is from both sides of the coin.....id take double rooks in most situations...

I think it would depend largely on the pawn structure. I would take the R+N+B as long as all of my pieces could defend each other. Then all you have to do is try to trade off your rook so it becomes a rook vs knight + Bishop, in which case i would gladly take the two pieces.