Cheers!, I don't own fibre-lyte, I just work for the company at the moment. Our special projects engineer who does all the repairs has made his own frame before and his own wheels but they are time consuming to do and as silly as this might sound, when you're around carbon fibre and manufacturing it all the time, it's nice to think about something different such as alloys that we don't use. Of course, if we wanted to manufacture the lightest, stiffest frame around, carbon fibre would be what we would choose, but I always find it interesting to see what other materials there are and how people feel about them. Boo bicycles in the US for instance manufacture bamboo frames. I also really like all the frames that Rob English at English cycles builds and I think they're all steel. I'm sure there are a fair few frames at the NAHBS that aren't carbon as well. That Rocky Mountain does look a nice bike although I was predominantly thinking hardtail, although I didn't mention it.
I hadn't really included aluminium alloy as it's not really a material that I've seen used on custom or high end builds, it seems more mass produced, but there's no reason not to include it.
@TheRookie, from what I've read, steel frames do seem to be getting down to sub 1.5kg frame weight. As for the top end, we've seen our share of sub 1kg frames and they are taking minimal to a new level. On a custom, hand built hand laid frame, by a specialist, sub 1kg is fine. On a mass produced frame built by a production line worker with few skills, I'm not so sure. Just my opinion
What has swayed myself towards alloys is the number of riders/customers who love their alloy frames over carbon ones, despite the extra weight. I get little opportunity to ride mtb's, but my view of road bikes varies. I love my carbon Storck but I've ridden other carbon frames that I've really disliked. My day to day ride is an alloy Litespeed (9 years old I think) and that's very comfortable but a bit flexy and certainly not as fast feeling as the Storck.