Most of my travel is on AA and DL which is why I put my miles into AS MVP. I used to have accounts on both DL and AA and I'd never get enough miles in one or the other of them to really do me any good. By combining them I've hit MVP this year and will hit my mileage for MVPG on Dec. 23rd flying an AA flight back from FLL. Now that the Delta deal is in place it's an even better deal and is AS gets the deal with AA sorted out then I'll be golden.
In short, I think it's a good way to go.