I've actually tested an H2 15". A few boxes (all ported) and at a couple different amounts of wattage. It did very well in 3.5cuft ported, however doesn't like big boxes (anything over 4cuft). I ran upto 2500watts, which is it's peak and rightfully so, I didn't feel as it could handle too much more than that (other than for burps). It performed nicely off 2000-2200watts though. Good sound quality, comparable to a Brahma or XXX. Very nice all-around sub that can very loud...
For sake of comparison, at 3.5cuft w/2300-2400watts it was 1db ahead of the XXX in the same size box and same power. In anything bigger than 3.5cuft and/or with more than 2400watts, the XXX was a few db's ahead.
Same vehicle and same meter....