Sure, diet and exercise are easier. I've done it for years, and I've lost the same 20 pounds about a dozen times! Losing the weight is not the issue. It's keeping the weight off that is so hard. For me, banding was the end result of years of weight struggles, failing on every diet I ever tried, and realizing the clock was ticking. I'm not a young man, and how many more years of life would I have before chronic gross obesity finally killed me? Bandng was a fantastic option for me, and allowed me to finally get my weight under control. I will never look back, nor will I go back to being obese.
Now, nearly a year after surgery, I've lost 125 pounds. I have had ZERO reflux, slippage, vomiting, hair loss, not enjoying alcohol, water not going down, or pills not going down. I've been stuck a few times, and each time it was because I ate wrong. If I pay attention and eat as a bandster should, I do not get stuck, and I can eat anything I want. I've had seven fills, the last three of which were very small, to tweak my "green zone" so my band works properly. Fills are no worse than getting a shot. It's a non-issue. Constipation is related to what I'm eating, and how much Fiber I'm taking in. My digestion has slowed down because of my diet, but it's another non-issue. I take fiber as part of my daily diet, and when it's time to visit the bathroom, there are no issues on that score. It's a small price to pay for being over a hundred pounds lighter.
The decision you need to make is how many more years (and times) are you going to "get serious about diet?" If you could do it that way, you wouldn't be obese now, right? My honest advice is that if you have any doubts of being able to "get serious about diet," then have the surgery. If it doesn't work for you, then have it removed, and go back to chronic dieting. You have nothing to lose but your excess weight, right?
Good luck!
Dave