yeah the ep2500 will make a big difference
ib's are subtle yet very strong bass as you would've heard at norpus's place ( l'm yet to hear his setup , but have an ib myself with 4 avalanche drivers), my last sub was a custom 15" ported job and was of good quality imo, and coming from that to the ib was a culture change thats for sure , the ib just digs so deep compared to the other while the ported one had a little more top end punch . l'm sure once l eq things l'll get that back with the ib as well.
l had a mate come over on the weekend for a demo of the ht and he'd just been to see eric clapton a couple of nights prior to this, and after a session of some music dvd's ( one with eric clapton in CREAM ) and of course just to show of the ib wotw ........ he was totally gobsmacked, saying if he had a system like this he'd doubt he'd ever go to a concert again , let alone the movies!
So collo l think you'll be pretty happy once you get things dialed in and loosen those drivers up a bit
cya Ken