I had the Bionic for a week, for me it just wasn't enough of an upgrade over the Droid X for me to keep it. I understand your concerns about your Bionic becoming laggy/glitchy at some point during it's life cycle. I have yet to have a Motorola phone that didn't become slow and laggy with some sort of glitch before my upgrade.
I've had a Razor " flip ", Droid 1, Motorola flip phone that I can't remember the model, and a Droid X and EVERY single one became laggy with in 6 months to a year. I'm almost to the point I don't know if I'll ever buy another Moto phone again. Google buying them may change my mind in the future.
I will admit I enjoyed every Moto phone I ever had until they ALL started messing up, it's not an issue with design and features, it seems to be a issue with using cheap parts to build the damn things.
I didn't own the Bionic long enough to compare that phone to the Nexus, but I do know with all Moto smart phones they have Moto Blur, and I have to say I miss having a UI on my smart phone. If I could get a Bionic or Razr Maxx and know for a fact for the FIRST TIME I'd get a Moto phone that didn't ever have lag/glitch issues I'd go Moto over the Nexus.
I really miss having a UI, if the Nexus had one I would most likely love it, but if it did I suppose it would defeat the purpose of the vanilla experience. On that note if your not a hacker/modder the vanilla experience might not be for you.
Since the OTA update the Nexus is a solid phone, but after using it for 6 months I'd have to say to anyone asking about buying one, if your not going to mod or hack the phone you may not like the plain interface. This phone truly is meant for you to make it your own, and if you don't do that like me, you may be disappointed.
I do want to say, I've had ZERO lag or any kind of glitching with this phone, and I'm at the point in the life cycle I started having issues with ALL my Moto phones.
I wish they had two versions of this phone, a user interface that makes things simple and add's features for the average user, and this version for the modders....
The version of blur that is on the Bionic is pretty light and didn't add a whole lot of UI. What is it that you miss? I know I don't miss the lag!