I exchanged my excellent (but somewhat problematic) Bionic for the RAZR on day one, at Costco. I felt like crap doing so, mostly because the Bionic (like DX and OG) is an amazing device! It was a little heavier and thicker than I'd like, but felt great in the hand. The pentile screen made me question the purchase in the beginning, but it grew on me and after a couple of weeks, I didn't even notice the pentile effects. I ended up loving the screen, imagine that lol.
My Bionic lost data like crazy though, something I cannot tolerate due to my past experiences with Motorola's excellent reception reliability (They really spoiled me!). That, and the creaky plastic back reminded me often how the Bionic was not as solid as every other Moto smartphone I've had in the past.
With that idea planted in my head, I decided to do the exchange (despite losing the incredible accessory package that came with the Bionic). The first thing I noticed was not the size or weight, but the screen... After getting used to the Bionic's screen and appreciating its functionality, the RAZR's screen scared the crap out of me. I noticed immediately a greenish tint (to white/gray) at low brightness, and the bluish tint (entire screen) when viewed on any angle. The colors are also over-saturated. These are far more noticeable than the pentile effects IMO. I feel the Bionic's screen is superior and if I could drop it in the RAZR's body, I would. I am getting used to the RAZR's screen though, and it doesn't take much away from the amazing product that it is. The data has been good so far, but this seems to be an issue that can surface in any random amount of time.
I wanted a phone that would keep me happy for at least two years, and I believe this is the only phone that could. I've considered the Nexus and HTC, but build quality, voice reliability and quality, and battery life matter most to me, and I feel Motorola focuses on these attributes.
I'm glad I made the exchange, but if I couldn't get the RAZR, a little hidden electrical tape to end the creaking back cover on the Bionic, and a patch to fix the data issues, would certainly keep me happy for as long as I expect.
Good luck on your decision, it is a tough one!