Even though I am not happy with my band lately, I have to agree with another poster that the pars flaccida technique was a likely culprit. Also, earlier on, they were shy on filling bands and didn't know how to do them successfully. So, the success rates would reflect that.
Now... I do think the band is a wonderful weight loss surgery tool, but yes, it does have its faults. If I knew I'd obstruct when my allergies get bad or if I get a cold I'd obstruct or that I'd obstruct when I swim or that I'd obstruct after flying or... etc. I might have reconsidered the band...