Gang,
Wen, I know this is news and probably worthy of mention, it might have been better to place this in the Bionic Hacks forum where folks could get more info. I hope they go there anyway, but my experience is that there will be lots who do not. I also hope the folks will visit the D3 hack forum where they can see what all has been going on with rooting, and the PROBLEMS some folks are having soft bricking their phones.
To the question of going back, at some point it will be easier, hopefully. Right now there is no recovery for the Bionic, and certainly no SBF file to return the phone to stock, so there are things that can be done to make the phone look like stock, but these are manual. And I say hopefully, as one of the reasons I have a Bionic coming is that there should be a reasonable amount of development work going on with this phone. The D1 was an anomoly by today's standards. Back when it came out, it was mostly the one and only phone, so everyone threw development at it. And its bootloader was not locked down tight, so Recovery was had in reasonably short order. The D3 has been out weeks, and does not have a recovery, Bootstrap bypass to Roms, or anything other than root. We (Bionic users) benefitted by the work done to root their phone, and hopefully there will be enough interest by developers for the Bionic that folks (developers) will hit the Bionic hard as far as working around the locked bootloader, and both the Bionic and D3 will have something more than just root in a reasonably short anount of time.
In the mean time, I would encourage folks to at least run their stock Bionic long enough to ensure that there are no obvious hardware issues that would make the phone need to go back immediately, before they root. If you do root right away, and immediately start removing bloat, it does come with the risk of difficulty getting back to stock and the fact that there will likley be some issues with the OS that will need "fixing" by moto/vzw by an OTA. This fix via OTA is just my observation looking at all of the phones that have come out since the D1. If your phone is modified heavily while rooted, the/any OTA could be problematic. Folks need to remember that with the D1, since it was rooted, recovered and rommed early, it was easy for the Dev's to snag the OTA's, and modify them for the rooted/rommed phones. No such luxory with the Bionic yet.
So the potential pitfalls are more than just not being able to return to stock (at face value). The implications with non-stock are returning the phone, receiving OTA's and going too crazy with bloat removal that you soft brick the phone.
Just my 2 bits,
Craig