Thanks for the input gents, I have looked at the Kali helmets, but I am a rather large individual and generally take a XXL helmet and the Kali's go to XL --- I have found the Fox helmet pictured at a couple of online sites ----
Fly has some full face helmets listed as MTB helmets , but on further inspection they just appear to be the carbon/Kevlar versions of the MX helmets
I had been considering just using my Bell super D type helmet, but the thought of getting my teeth cleaned out in a rock garden is not pleasant
LOL --- there's nothing cheap about downhill stuff is there