B.S. covered everything I was going to contribute. I'm running 600w into my Low B2 and the thing sounds amazing.
Andy Lewis (the manufacturer) admits that the 350-watt nominal power rating listed on the Acme website (www.acmebass.com) is probably a minimum and that 500 watts may be more realistic....but, if you've got the clean power, I know of no other 2x10 (admittedly I haven't yet tried them all yet) that provides better clean, clear response across the frequency spectrum AND it delivers a low "B" that I find second to none.
+1 on the Acme! I m running it with 600w. Never been happier.