OK, here's my .02
Night and day difference - I just went from a Carver C1000A (5 x 200w@8ohms/300w@4ohms) to a Lexicon MC-8 and Gemstone 7 x 200w@8ohms/400w@4ohms) driving 4 ohm,fairly efficient speakers. Given the similar power capabilities and discounting the 5.1/7.1 difference and the newer decoding formats, the pure audio performance is very close - I wouldn't say "night and day" difference. But you've got to take into consideration the receiver you're starting with and it's power output & speaker impedance capabilities.
Now you've got a full-featured, late model receiver. I think you'll be hard pressed to find comparable separates within your budget (including all processing and switching capabilities of the 3805) that will significantly surpass the 3805's power output...
A better starting place might be to keep your receiver and use it as a processor and get something like the Outlaw 7x200 amp to drive your speakers. I don't know the efficiency/impedence of the Axioms to know if they might be taxing your receiver when driving 7 speakers. Another option would be to get separate amplification for your left+right+center and let your receiver do the surrounds...
Those are my pennies!
Wyatt