Hi Jen,
"Permanent" is a tricky term relative to this subject. One might ask "Can one lose weight permanently from dieting?" Well, sure, but a person is just as likely to put all the weight (and more) back on as soon as the focus on dieting passes. It's the same thing with tight lacing.
I've never had a gastric band, but I've heard it said that wearing a tight laced corset has a similar effect on the stomach, but without all the messy surgery. I can attest to the fact that what and how much I'm able to eat (or drink) is dramatically effected by wearing a corset. The stomach does not have room to expand when I eat. Over eating has terrible consequences in the form of pain, indigestion and even regurgitation. Consuming things with bubbles (like soda) has similar consequences. So, in a sense, wearing a tight laced corset is kind of like being on a diet.
As long as I keep wearing the corset, then the changes to my body are permanent. If I stop wearing corsets but continue to eat a sensible diet, well, my body will revert to it's pre-corset shape to a certain extent, but I'll probably be able to "permanently" maintain much of the slimming effect that I've achieved around my midsection. However, if I stop wearing corsets AND revert back to old habits of eating, well, then all bets are off. Not only will the changes that I've achieved as a tight lacer not be permanent, but I could possibly end up even more overweight than I was 7 months ago if I allowed myself to slip that far.
So, the simple answer to your question is that changing the shape of your body through the use of corsets is as permanent as a haircut. If you keep getting your hair cut in the same way, well then it can seem like a permanent change to your hairstyle. But skip a few hair appointments and you'll find out how UN-permanent such changes really are. Tight lacing is just like that.
If you decide to tight lace, inform yourself, be careful not to hurt yourself, and most importantly, have a lot of fun with it!
Hugs,
Miharu