After reading the UA, and considering Monte Cook's work on AU, I reach the following conclusion: since a gestalt character is basically able to handle twice as much with regard to encounters/challenges for a gestalt character should be twice as hard as they would be normally. Ergo, the level adjustment for a gestalt character would be equal to the average of his/her two class levels (e.g. a 4th level gestalt character would have an LA of +4, a 16th level gestalt character would have an LA of +16). As he/she gets more powerful, so do the challenges - as it was meant to be. For a party of characters, just average out the LA. As for one type of gestalt combo being more powerful than the next, if all classes are presumed balanced to begin with, this is not really possible, is it? The DM is the one responsible for handling in-game situational balance on a case by case basis. Just letting a gestalt PC get away with a one-time LA pay-off is ultimately damaging to the game as a whole (unless its a munchkin/monty haul campaign, in which case, who cares, really?).
At least, that's my opinion...