Aggree with @oddiofyl above -- sacrificing the Extremas + a few k will NOT buy you significantly better speakers... Maybe the Eidolons - if they're going for very cheap nowadays BUT the sound is far from what you're used to.
IMO, the best thing to do is:
a) buy 1-2 subs (SVS are excellent value for money)
b) model your room (REW is wonderful and free)
c) place subs accordingly.
In my room the sub is facing the main speakers and brings clarity and punch to the bass.
Good luck those are nice speakers - I had a pair back in the day!