I received the same email, not knowing if he couldn't just do a search, and me not knowing much about FatBike wheels, I did a quick search and sent him back some info.  To my surprise, there are already several carbon fat bike wheels on the market.

Below is my reply.

https://www.hedcycling.com/bigdeal/
https://www.hedcycling.com/pdf/HedFatRimInstructions.pdf
http://www.lamerecycles.com/#!fatbike/c1ff7

This website has some specs:
http://sarmabikes.com/products/carbon-rim-fatbikes
ERD: 534 mm
ERTRO: 559 mm
Recommended tire pressure: 10-15 PSI
Max rider weight limit: 110 kg
Max Spoke Tension: 100 kgf
Recommended valve’s length: 35 mm
Recommended width of tubeless tape 50-65 mm
Recommended spokes nipples: 12 mm

http://www.borealisbikes.com/parts/carbondale-rims/
http://www.bikerumor.com/2014/02/25/exclusive-kuroshiro-reinvents-the-tubeless-wheel-with-their-incredible-enso685-carbon-fat-bike-rim/
http://fat-bike.com/2014/02/sarma-introduces-first-100mm-carbon-rims-the-naran-100/

Also, I would suggest ordering a set of wheels you like from one of these places to get more specs.
Regards,

If you are going with one bike as an all-arounder, I would lean toward a FS --- I went with 057...happy with it....but, not going to have a stable of bikes a FS with lockouts would do overall.
If one knows what their goal in riding is:  XC riding for example get the 057(or similar) and build as nice a bike as budget allows.
I know I went in thinking I could build a nicer bike, with nicer parts, for cheaper.  Well, I got into it and went over budget.

I agree with you in that if I had only one bike, and rode mostly XC single track, a FM-057 hardtail is a great choice.  The way the carbon smooths out the ride over my AL frame bike is simply amazing.  With less fatigue and a lighter weight bike also comes more speed, which is why I'm even faster on my carbon bike than I ever was on my old Aluminium bikes, hardtail or full suspension.

You already have some of the trickle down technology with the clutched rear derailleur and the wide/narrow chainrings, and 42T cogs that people are making for 10-sod cassettes.  When XX1 came out, it was very unique, now it doesn't have as much of an advantage with those technologies now available other ways.

since the 29er is too big and  the 26 is too small, the 650b is the excellent choice!

Everyone has their own opinion but for my size (6'-0" 190lbs) for me 27.5 is still a bit small, 29" fits me well.

Good to hear you got the frame so quickly.  Waiting for you to post pics.

Updated first post with general build order.  In preparation for doing a more detailed build instruction aimed at someone who has never built a bike before.

The package will be handed off to USPS, you can track it there once it gets to the US.

I know what you mean about the Easton Carbon, they make nice looking stuff.

Andy, it's interesting to me that you work in a bike shop.  While I was shopping around deciding what FS bike I wanted, I looked seriously at the Specialized EPIC Expert Carbon but I could not see $7k for a new bike that didn't have the XT brakes, carbon bars, or carbon seat post.  To be equivalent to my IP-036 build I would need to spend another $500 and I would have paid tax on the EPIC so I'd be in for $8k.  I built the IP-036 for half that.  Granted I don't have a Brain shock front and rear but the last review from Bike Magazine was not all that favorable and they decided the bike worked best with the rear suspension locked out the whole ride.

Admittedly the big name brands do have high quality frames, probably use better bearings in the pivots, nice paint jobs with lots of  graphics with letters and numbers but they don't ride twice as good.