My mentor, who has been recording orchestras since the late 60's, feels that it is generally best to not remove energy from the room, so he would prefer diffusion to absorption. He also does not like cylindrical diffusors--he says, "they scatter too much". And I saw a studio reworking where they made the room somewhat more controlled and also put half-round cylindrical diffusers on the [high] ceiling and I felt the room unquestionably lost some magic.
Having said all that, he's used to working in big spaces. To me (who works more in medium-sized and smaller rooms), I don't like rooms that are too 'dead' because they seem compressed and lifeless. But I also don't like rooms where--if you record multiple passes, or multiple instruments in the same space (but at different times)--you hear the sonic signature of that space becoming more and more obvious as it becomes part of the recording 2, 3 and even more times.
In my mix room I have an 'acoustic cloud' of 4 RPG Skyline diffusers around 28" above my head and that works great: I don't feel like I hear the ceiling, even though it's only around 7 1/2 feet high. But some people say if you get too close to diffusers, things start to sound 'phasey'. So part of the answer is probably in what you want to record in the room. I like Skylines a lot. Yes, I know they're expensive, but there is no easy way to build them yourself, I have 12 in total and I'd be really bummed if they were removed from the room.