my dad demoed the paradigm 100 v3 w/ his 2805 & was happy with the result once we bi-amped the 2805 (instructions for doing so are somewhere else on the forum under perhaps the 3805 review??), so you might want to try this first before buying a seperate amp. i'm a big fan of the 100 v4, but have not heard the v4 run with a receiver, only with seperates. it offers alot (but not all) of the sound of the signature line at a greatly reduced price.
my other suggestion would be to skip the receiver alltogether & buy a seperate pre-pro & multi channel amp. i started w/ a 2805, later added an amp after alot of demos w/ good results, but as big a difference in overall sound quality was replacing the 2805 w/ an anthem avm 30 pre-pro. if your considering seperates, i would recommend going that direction from the beginning to save some money overall.