I get details are important for a few people but I wouldn't get to caught up on what the guys over at RPF say about the bridge. I mean really - 9% too big? On whose authority is it too big? Its a fictional ship in a Sci-Fi movie that used a lot if different miniatures - each one a different size. Don't get me wrong - I LOVE Star Wars and Science Fiction but it ticks me off when people start rivet counting something that just doesn't exist. Sure - you can see obvious flaws in kits like the AMT version but at that time, it was the only kit around and if you have the time, its fun to make it "accurate" (or at least add some more details to it) but the Zvezda kit is a really nicely detailed, beautiful kit and I can't wait to start mine. There are some parts where detail is lacking but again, personal preference will dictate what you do about it - if anything. I'm OCD enough to do something about it
In regards to AM parts, you can get some from Shapeways or another place here: http://www.falcon3dparts.com/sd_upgrade/
I have bought a set for myself and am waiting for them to be printed and sent. Hopefully, it's not a scam but I am covered by PayPal anyways if it is
Just have fun with it