I used to deadlift heavy (320 kg for 2 or 3 reps on the heavy set), I never wore a belt until we went to 5 plates or more. The more our core muscles worked the better, by not using a belt you force the anciliary muscles to work more and ensure you are totally in control all the way through.
The reason we did use a belt was because of the increased risk of injury on the heaviest sets through possibly not being in as much control as we were on the lighter sets and whilst not being able to cheat on deadlifts our form may have sufferred when attempting to move such weights.
The same went for squats (270 for 5 on heavy set), no belt until 5 plates and no wraps until 6 plates a side or more. At the end we never wore the wraps at all.
It worked for us, we got stronger and thicker like we never believed, the beauty of this training is that after almost 5 years of serious medical issues (I was given a year to live 5 years ago!) and only having managed 18-24 months since then I still manage to hold onto a serious amount of muscle which flys back on whenever I start back.
We called it "power bodybuilding" because we encorporated powerlifting movements and poundages with drop sets and isolation movements, my training partner and I did/do not have great genetics but we carried serious amounts of muscle (17'2 with abs at 5'9.5).
www.extremenutrition.co.uk