The new Pioneer Class D3 amps are an improvement over their previous Class D Ice amps. They have also been engineered to perform with 4 Ohm loads. While this isn't too important with your 8 Ohm KEF IQ's (nice speakers by the way), it should provide peace of mind that the Pioneer will provide you with more than adequate power. The 1222K also appears to be a clone of the SC-61/63 and looks like a good value at their current street price. I have owned three Pioneer AVR's over the years, currently having an SC-25, and have had no problems with any of the them. I am sure the Yamaha is a good AVR and you will probably hear from their owners too. Needless to say however, my vote is for the Pioneer. Good luck in your decision.
Marantz PM15S2 LE, Oppo BDP-103, Simaudio Moon 100D DAC
VPI Traveler V2 with an Ortofon Rondo Blue and Simaudio Moon 110LP, Technics SL-1400 with an Audio Technica AT-14sa and Pro-ject Phono Box S
Dynaudio Focus 260's, Rel T-1 and a Panasonic TC-P54S1.