So I bought one of these a month ago. I've worn 1/2 helmets for 25+ years with out any issues, including one major crash. The way I looked at it was you get a Sena & helmet for the price of the Sena unit. The Calvary, good helmet, comfortable, fits well. Priced at $299 + tax on sale. You will have issues hearing anything at speeds over 50mph, road noise. Bought NoNoise, noise canceling, earplugs after the shop where I got the helmet recommended them. They made a world of difference, with the side panels on the helmet I can hear music just fine. I haven't tried to have a phone conversation yet, kinda why I ride, to disconnect.
As to the comments about buying a helmet from a BT maker and not a helmet maker. The helmet industry is like any other, they buy blanks from manufacturers, lowest bidders and finish them out with their name on them. How much difference is there between a $200 helmet and a $800 helmet when both meet DOT standards? I think my first FF helmet cost $40 of course that was in 1978.
Currently Cycle Gear has Bilt Helmets, both modular and full face, with built in Sena units on sale for $229, that's less than the Sena unit itself. I tried several of these out the other day, sizing runs 1-2 sizes small. I normally wear a medium but the Bilt helmets I need an XL or XXL. Currently undecided on whether to get one but probably will.