The last time I got to use both the 212 and 115 on a gig I had the 212 on top. However, at home I've found that the 115 on top has a more pleasing tone closer to ear level. They compliment each other well, but as I've said probably a dozen or more times on here already - the 115 is the absolute gem of the whole line. There isn't a single 1x15 of anything I've ever tried (combos, cabs, etc) in the 25+ years I've been playing that sounds anything like it. Whereas years ago a 15" cab might have been used to round out some low end with a 210 or 410 cab and rarely used solo, this thing is about as musically pleasing as it gets.
I also discovered with this cab that the tweeter does a lot more than just produce highs. I had a rehearsal where I experimented and completely rolled it off compared to keeping the dial being at noon. Wow, talk about a night and day difference. What I found happened is that it took a lot of the mid character with it as well and not in a way I would have ever expected nor to my liking. The old school way of rolling off the tweeter to kill the highs does not apply to this cab the same way. I asked Andy about it and I could tell that he seemed pleased I found a little hidden bit of clever engineering in his design.