Well here are some of my brief thoughts:
I have 3 kids and a class B (a PW Travato). Once you have had a class B for trips (even just for an afternoon) it would be hard to tolerate anything else. The extra room, the fridge, the potty, the furnace (if you need to wait somewhere cold) all combine to make travel and parking far more pleasant with kids. We use ours all the time and absolutely love it. Of course it is too small, so we have been looking at larger ones like the Roadtrek models you mentioned. Like you, we have our financial ducks in a row and can purchase one of these without irreparably harming our ability to retire, pay for college, etc.
My whole family (kids & all) went to the Hershey PA RV show the year before last and spent the better part of two days climbing in, out, and all over all of the class B models where were on display (which was pretty much all of them - Hershey is the biggest show in the country). It took very little time for us to cross the Roadtrek Sprinter models off of our shopping list. I wrote a post describing our impressions which you can see here (
Thoughts from the RV show)
The issues we identified that bothered us may not bother you. One ongoing concern I have however is how well the more complicated class b vans will hold up under even moderate winter usage in the northeast. The road salt can be tough on exposed parts, and there are a lot of exposed parts under these vans.
