I have a Specialized Echelon that I'm currently using (it was free- won a LG time trial helmet from LBS but was allowed to exchange). I've tried mounting my cheap light that's powered by 3xAAA using rubber bands, but either I can't get the aim right or it flops around too much. And the zip tie trick didn't work for me either .
Also, since I'm a bike/bus commuter, I only wear the helmet while on the bike. The helmet either goes in a backpack or dangles from the top haul loop. Not sure I'd trust a lockblock to hold a light when it's flopping around on the outside of a bag like that, but maybe the mount by itself (with the light removed) would be okay?
Litespeed Liege, Motorola Team Issue Eddy Mercxk, Surly Crosscheck Cyclocross bike, Fisher Supercaliber Mtn. Bike
For those focused on a good helmet mount, look at the zefal doodad plus. This is normally used to mount a bike pump but works great as a helmet light mount.. The twofish bike block - it has parallel mounting is a good one too.. I found that the mount you use is different for each type of helmet, so it is best to try a couple different models and see what works best.