Upload & Sell: Off
Running both programs involves a whole lot of duplication of effort. I'd rather just wait until bleeding-edge users have found all of the significant (damaging) bugs.
Thanks for the additional info. Since Adobe has acknowledged the Nik plug-in issue, I'm feeling a little better that they will have a fix for it, and hence I'm now not that concerned with the upgrade to LR4 (though I'll likely wait a month or two).