the x-tek thread has a lot of information on it.
Sta is determined by the wing, not the backplate,
i can't think of any backplates that don't have cam band slots anymore, though there is a dive rite plate without them in my living room right now.
Xt-lite isn't going to do a whole lot for taking weight off of your belt though i suspect you're still overweighted by a bit and switching to a bp/w will likely shed a few pounds just by nature of wing vs massive stab jacket. Xt-lite is only about 2lbs, so you'll want a full ss plate to shed 5lbs. If you're going to be flying to destinations outside of the country and can't put it in a carryon then it might factor in, but for local diving get the heaviest plate you can. Depending on cost, dss does make a large plate which is wider than others and weighs close to 6lbs vs 5lbs of normal sized plates, they also sell weight plates that can bolt onto the backplate which are 8lbs for that pair. So with ss cam bands at 1lb each, you can take 16lbs off of your belt with that setup. Downside is it isn't cheap, $330 for the backplate and weight plates, but their weight plates only fit their rig and depending on how antsy you are to ditch lead, it may help.
Oxycheq wings are very high quality but they use a very thick inner bladder material that is not particularly easy to pack because it is very stiff, cs is probably not the best in the industry if you have issues, but you shouldn't have any issues.
cave adventurers - single tank wings - marianna, florida usa - never undersold!
i understand supporting lds, but make sure you aren't getting ripped off, edd has great pricing and if you call may be even lower, the wings are very expensive though.
Steel tanks will also help your situation, worthington hp 100's over the other brands are 2.5lbs negative when empty vs most other hp steels at 1.3, so that alone will take 7lbs off of your weight belt vs an al80. Pst lp104's are 3.3lbs negative and you can usually find a set of double 104's for $400-$500, break them into singles, and if you buy the dss plate with the weight plates that would take away your weight belt altogether.
As far as shops go, before you buy, go visit crazy john at northeast scuba supply, he is a great resource, great instructor/diver, and always has some great deals on gear. He is a deep sea supply dealer, as well as oxycheq, dive rite, and many others.