It sounds like you're trying to talk yourself into going full frame, Tom.
Oh, I already have a full frame body - the 5Dc. It does handle noise better than the 50D - by about a stop and a third. However, it lacks the pixel density, which is often very necessary for the subjects/situations I shoot.
I empathize with you, but at the same time if you are a professional working photographer, why don't you upgrade to a camera that better suits your needs?
There's a simple reason why: money. I simply do not have the cash required for a suitable upgrade. And a loan is out of the question, because I doubt I would ever be able to make the payments. So, I just have to continue to live with the frustration of having gear that is inferior than that of my competitors until I can get the money together for a 1D4 - which will probably be another year and a half (hopefully they drop down to the sub-$2000 range by then).
KFReels was very right when he commented, "Sometimes not good enough is . . . not good enough".

