Aerial Sw 12 vs Revel B 15 Subs ?

I have heard the SW12 and the B25 but not side by side so it's difficult to say which is better. However, I did purchase the B15 and it's used for 2 channel music and HT. The B15 does have a few advantages over the SW12 - $1500 less, more features and larger driver. The 3 band parametric EQ is very useful in controlling room interaction. I have the B15 crossed over at 40 Hz and it blends in very well with the Revel Studios.
It also works very well for HT. I have not heard it bottoming out yet. The most bass I have experienced is the Lord Of The Ring DVD and it didn't stress the B15.
I have had the B15 for over a year now and I am still pretty happy with it. I may add another B15 later on.

Aerial's bass is tighter, and I think it is a lot more tune-able, so its less room dependant. However, if you already have Revel speakers you couldn't do much better than matching it to a B15.

Besides potential power handling, I can tell you that the major factor here for you is going to be PROPER SET UP, CALIBRATION, AND SPEAKER/SEATING LOCATION for your bass performance!!!(far greater than any small differences in potential performance characteristics between the two!)
The Revel is going to be a better HT sub however, I can tell you that. It will have more dynamic headroom and output I believe. Also, the Revel has the VERY VALUABLE EQ ON BOARD!!!(you can put on on the Arial to be fair).
Still, getting a MUCH MORE AFFORDABLE Paradigm Servo 15 is going to yeild you the same high level performance for less!(if you're after a single woofer sub that is). You could almost get two Servo 15's for the price of one Revel B15, and put a Parametric EQ on em if you wish!...It's a thought.
Still, I'd chose the Revel over the Arial for HT/music dubties...even if you do do more music than HT. I know for a fact that I could get tremendous sound performance for music with proper set up and tweeking of the sub(that's the key to great performance from ANY SUB SET-UP!!!).
good luck