I used one for over a year, do not do it. They are crap.
[1] Far too heavy.
[2] Mic is very prone to condensation problems.
[3] The visor edges are inside the helmet shell when down so that in the event of an impact the visor edge is pushed in-between the helmet and yer head.
[4] External dimensions - apart from making you look like Princess Leah - restricts head movement in many types.