I have 5 superzero 2.0s and cross them over a 100hz and it sounds great. Try lowering your crossover to 100 and see how it sounds. I ran the SZs for awhile when waiting for my sub and they have more bass than I was expecting. NHT lists the -3db point at 85hz (IIRC).
I have no experience with the subs you've mentioned.
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron