Thanks, everyone, for the feedback. Gives me a bit to think about. If I do this, I think I will go for the QD1.
I cleaned up the links in the first post, correcting also the weight of the current tent (6 and a half pounds, not 8 and a half).
The nice thing about the current tent is it big enough to bring the bike inside if I have to, or it can comfortably sleep 2 people. (So, is 3 or 4 pounds and the extra bulk worth the peace of mind?)