I've just ordered one from him. This helmet is a collaboration between RedMan, JJ Industries, and the man himself, Darren Pattenden, aka. Great Ape Studios. His design is THE standard for approval into the 501st, and all his files are top-notch.
Waiting for it in the mail, but in the meantime, I will continue working on the one I've printed myself from Mystery Makers, which was scaled down to 94% based on the size from Great Ape/RedMan helmet.