I've gone back and forth on this subject, whether I should sell my Fine Molds kit to put towards the Bandai kit, and how imperative is it to get the Bandai kit.
As Real G pointed out, each kit is a copy from a different studio model, which themselves have different proportions. The 32" studio model is flatter, less chunky than the 5' hence the Fine Molds kit looks flatter than the 5' model. The Bandai version is the New Hope version, which differs significantly from the Fine Molds Empire Strikes Back version. Even so, the Fine Molds kit is a bit flatter than it should be, the mandibles don't toe in as they should and they may be a bit too long. On the other side of it, I took out my Fine Molds kit and dry fitted the upper and lower halves to get a general impression of how it looks completed and, to me, it looks fine. The detailing is excellent - again, there are some flaws, but only to the eye of a Falcon expert - and the flatter look makes it sleeker looking to me.
The other consideration is if you don't buy when it's released, what will availability be like later? Is this a "once in a lifetime" opportunity? Considering the price point, I don't think it will necessarily fly off the shelves and I think so long as they keep making Star Wars movies, Bandai will keep cranking them out. This is speculation, of course.
So, what I decided is I'm keeping my Fine Molds kit. I'll have an Empire Strikes Back version more closely matching the 32" model. If I happen upon $500 CDN in August (or later) and I can get the Bandai kt, I will. If not, I'll still sleep well at night.