I have no experience with their new tuning service but given my experience with their own shocks I would expect a great product and excellent customer service. When you purchase a new shock from them they custom tune it to your bike, weight, and riding style. If you call them up you will almost always be talking to Craig, the owner and person who will be doing the work. My last experience with them they changed the stroke length of my shock so that I could put it on a different bike for the same cost as re-valving it (and not much more than what fox would charge for a re-build after warranty expiry). This is a great service if you have something other than fox or rock shox which is already done by Push. Hopefully Avy will get into tuning forks one of these days too.
I was part of the beta testing for their 5th/Swinger rebuild/revalve. They did the 5th on my ASX and it felt awesome afterwards. Very similar to the ROCO that replaced the stock 5th. If I still had the bike I'd let you ride but I sold it some time ago.
Give em a call and talk to Craig, he'll take his time answering your questions. I love my Avalanche shock with the generic shelf tune, i'm looking forward to the custom tune.
only 1 thing i dont like about avy... they wont let me do my own tunes. i cant buy just the parts. so instead of a few hiurs at most of down time, its potentially a week or so.