I use the Big Agnes Insulated Air Core air mattress, but not a Big Agnes sleeping bag. I do however like the idea of a pocket on the bag for the air mattress, which not only keeps you on the pad (not really a problem for me) but eliminates the need for bottom insulation in the bag.
I like the pad a lot. You are right that it is not self inflating, but that's exactly why I bought it. I wasn't comfortable on a 1.5" self-inflating pad, but I got the 2.5" Big Agnes for the same weight (but need to blow it up). I have blown it up a hundred times--it's not my favorite thing to do, but it's not excessively onerous.
I do, however, roll over a lot in my sleep. I have a mummy bag and the bag rolls over with me of course. The bag you have is not mummy, but I still might be concerned about how easy it would be to roll over in it. If it was me, I'd go to the store, climb in the bag and try it.