I have not used any but the Halcyon rig, but do love it and completely recomment it. As on another bp comfort thread going on here, I will say the solid piece of steel or alum is comfy without any extra padding. I think DR and OMS add the padding so it looks more comfy above the water, but I don't see it doing much under the water.
I would also add my observations that many people that originally bought or used a lot (me included) the back inflation BCs soon after saw the light of bp/wings. I completely agree with the DIR folks that the traditional bp/wings is the best rig for a first day in the water OW student to the 20 hour dives in Wakulla. Bouancy, trim, finning, etc are all easier (IMO) with the bp/wings.
I will plug the Halcyon here as Extreme Exposure will let you use any of their products for a month risk free, you just pay shipping, which from Fla. to NC was 15 or so each way. I asked about a scratch and dent discount on stuff that gets sent back and they were a bit dumfounded since only one thing had been sent back. They were also great at customer service. I dealt with Dave and Tamara. In fact, I ordered and used the 27 lb. wing and thought I might want the 36 lb. one, they would have switched the used one for a new one with no questions asked!
Tommy