Well, just updating the state of things here. I received my Samsung Vibrant from T-Mobile today. Taking away everything that is way better than the behold ii (bigger screen, 1ghz cpu), it's what Touchwiz and the Behold II should have been.
Having said that, I'll likely be rooting the phone, installing Modaco's custom rom, and running ADW.Launcher. Gonna give Touchwiz 3.0 and the Samsung social widgets a go for a few days before I decide.
And yes, it's already rooted. And yes MoDaCo already has a custom rom available that at least allows some customization, wifi tether, and removal of stock apps. And yes, Cyanogen now has a team member assigned to porting CM6 to the Vibrant/Galaxy S. So if you're thinking that the Vibrant is a potential repeat of the Behold II in the support dept, it's probably going to be orders of magnitude better in that regard.
I've installed all my usual favorite apps, tons of mp3's and video, and it's been great so far. It came with a half charge, so I spent the better part of the day (about 6 hours) draining the battery. It's on charger now, so let's hope battery life ends up being ok. It's already way better than the Behold II was for me with a ton of tweaks battery-life wise.
At the end of the day, T-Mobile did the right thing for me and though it took significant effort on my part I am now satisfied.
I'll leave off by giving a bit shout out to all you guys. This was a very helpful place and brought me up to speed on Android in general, and the Behold II specifically, in record time. So some of the credit for my success with my complaints definitely goes to you guys!
My hats off. Best of luck to you all!