It's not the power you're paying for with the 1120, it's almost a completely different receiver than the 1020. The 1120 is based off the Elite platform, and has a lot more features than the 1020. You should compare the feature set and see if the difference there makes up enough for the difference in price.
10 Watts means nothing in terms of sound. But the amps in the 1120 are of a different design than the 1020, that's why they are spec'd differently in terms of power.
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs