The 3805 seems to have all kinds of nice additions (a truly neat looking remote, for example), just seems like most of them won't affect the sound. Someone posted recently that only the 3805 has DenonLink -- that would be the only thing I would think about as being maybe worth extra $$...

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8