I was very hesitant to switch to non-RFTs on my 650. However, I ultimately switched to Michelin Pilot Sports last year and I must say the difference was immediately noticeable.
Also, when I had the new tires put on, the service tech had me pick up a new Pirelli RFT (actually hold it in my hands....) and compare the weight to non-RFT Michelins. The difference was significant. His opinion was that not only would I feel a smoother ride on the non-RFTs, I might also see improved MPG. I did--According to the OBC on essentially the same roads/mileage for a six month period, my MPG average went from 19.9 to 21.
The tech did say that the RFTs have proven to perform better on hard cornering. That's not something I do a lot, so it was less important to me.
MY2007 650 conv | Stratus Gray | Black Pearl | HUD | Night Vision | Sat | Logic 7 | RT Traffic | Cold Weather | 6-speed Euro Delivery completed 9/15/06
MY2008 X3 3.0si |Monaco Blue| Sand | Sport | Prem | NAV | Auto | Euro Delivery 9/21/07
2004 X5 4.4i (retired)