Accepting all the casual players from the merging/acquisition guild and letting them to continue to be casuals I think is very smart. It allows flexibility with pulling from a larger raid roster, since most casuals can be decently geared with little effort.
My biggest concerned about when my 10man guild was absorbed to a 25man is whether or not I would still be allowed in the guild if I didn't cut the mustard for the main progression raid team. To find out there were many other options like Weekend teams and 10 man teams in PvE and PvP put my mind at ease.
Also i think the multi-gaming guild is more attractive to most players. Knowing that they can get in some league play when they are occupying a bench slot is a plus.
I really want to hit this place up in October. I love it when hot Latino men come by my table and offer me their meat.