I have the 660 with NIM. I love it. Voice commands interrupt any music playing. No problems with touch screen sensitivity. The only difference between the 660 and the 665 is the XM. Though XM would be nice - I have the radio, an iPod, the CD (and MP3), and can use SD cards in the 660. So, I don't need another XM subscription (have 2 already). I was in some pretty serious rain the other day and had no issues with the 660.
'12 RGU; 17" Carlini Evil Apes; RSD Venturi Speed 5 A/C; V&H Power Duals with Monster Rounds; SE Perf Tuner; Slipstream HD grips and footboards; 14" Windvest; Ironaces GPS mount; Tour-pack Spoiler and Rack.