I'm a little curious... you say you've got 2000 watts to work with but you are going to "upgrade" your amplifier? If you mean down-size, then any one of the subs mentioned will be fine. The BTL will be the only one that can take, or come close to taking, 2000 watts all day. That...and there is no SQ in 2000 watts.
Now, if you want the ability to pound on occasion but still want good sound quality I highly suggest looking at a pair of drivers. 1000 watts per driver is more than enough power to push a sub to/past it's limit. The Icon's, Mag's, or a Brahma if you can find one are my top choices.