The release price of the XL is supposed to be 300 but since the demand is up and production is not full yet they are expensive, wait a bit. Who cares about Doom 3, HL2 is better and so is the engine, since ATI's recent models dont support PS3 game manufactorers know that and are not gonna penalize you all that much if at all for not having a 6800. They want everyone to play their game, they dont want Nvidia to win. The XL is supposed to be a full 100$ cheaper and yes with the benchmarks it is a much better deal.
I personally think that its stupid for ID and ATI not just ATI. They will sell less games since they pandered to Nvidia so badly, but Valve is doing great since their game supports both cards just fine albeit giving a small edge to ATI.