Hi Lucy
I only have personal experience of lap-banding in the sense that my mum had the surgery.
She weighed in at around 23 stone, had to go on a high protein (EVERYTHING was weighed - it was a kind of 'fasting' diet under the supervision of doctors) diet to show that she could lose some weight prior to surgery and had the op in the winter of 2003.
All in all she's lost about eight stones since then. However that took her to about april 06. She's had major problems with the band to be honest (and if I'm being honest I don't agree with the method that she chose but ho hum). Some foods get stuck/cause problems - the person (in this case my mum) coughs/chokes/retches (sorry if too descriptive). She did this so much she coughed up blood. Ended up in hospital - the band had slipped and she's spent the past year without any fluid in the band and just being 'normal' (as it were). She's put on 13kg.
They've agreed to put more liquid back in the band in the next few months as she still weighs in at 115kg approx.
Surgery wise from what I've gathered its a very simple procedure. She has a couple of small scars from the keyhole surgery on her tummy. She can feel the valve thingy (where they put the liquid in) under her skin though and says sometimes it causes discomfort on trouser waistbands etc. She had the surgery on the NHS and was one of two people in our health authority to be given the ok to have it. She is what the doctors consider a success story however I'm not so sure.
I'd never say don't do it - but I would say that the problems that she has - the overeating/eating the wrong things/not exercising - they're still there. She keeps looking to the band to do the work for her and I just don't agree with it.
Best of luck in your research though I don't want to put you for/against - just giving my personal family experience