I'm sure there is nothing wrong with the Alpha. It just seems to be almost double the price of the Gentex.
From what I've read it also seems a little heavier than the Gentex, and although I'm looking at getting a helmet for use in the Extra/Pitts when doing aerobatics I want to keep weight down if possible.
Unless the Alpha offers significant advantages over the Gentex to overvome it's heavier weight and increased cost it doesn't really seem worth it.
Of course, it is a minus if the Gentex can only be sourced direct in the US.