I totally agree with Pull and MAB, belts have helped me realize form mistakes and helped correct them. Any bonus in extra weight used will be negated as I move forward. And like OR, I too only use them at 95% or above so that I'm using the knowledge/strength I gained on lower weights. Pretty soon, my belted max will be a nonbelted max, and so on.
Only other thing I will note that hasn't been discussed is that safety effect a belt gives you when you are maxing out. If you get forward on a max squat or deadlift without a belt, your lower back is in serious trouble. A belt can save you and allow you to train again a week later, as opposed to maybe months or years later if you eff up some disc or tiny ass muscle in your lower back.
I am Anton Zdravko Martin!
Best meet lifts: Sq 150 Kg (330 lb), Bench 120 Kg (264), DL 160 (352) @89 Kg (197)
Best gym lifts: Sq 375, Bench 275 (pause), DL 370 @205 or less
Goals beyond my wildest dreams, 600 Kg raw total, 200/160/240
Hack away at anything which isn't essential. Do what you love, and do it often. Fazc.