I'd bet on SB
I'm in the end throes of slow building my RV-9 tanks now, and I can't see how you could run vent lines in a closed up tank.
BTW - it's not "that" bad.... when I'm done, if there are no leaks (fingers crossed), I'll post a list of tools/techniques that I used. I'm doing both tanks at the same time.
One last thing - I see you're in the lobbying phase (that lasted 20 minutes for me). When I started and before, I always swore I'd go quickbuild - I thought I'd never get it done otherwise. After building the tail I learned that slowbuild was for me. So far that is still the right decision. I've been moving along on it pretty well and I'll be glad to have that $8K to spend on other stuff later. Maybe you'll have the same experience,
good luck,