Hi Charlie, I already finished the trek. It was a great experience I recommend to everybody, specially if you live in a big city like Chengdu.
The trek was guided by myself and visited a very remote area near Litang, Tibetan monasteries lost in the mountains surrounded by snow peaks over 6000 meters high and a great opportunity to breath fresh and clean air.
If anybody has interest on doing a trekking like this you can contact me as I am working for a Spanish travel agency for trekking routes in China and Spain, usually there are chances to fit extra people in a group.
If not interested in joining a group I also do some treks by myself to find new routes to offer, for these ones I always prefer to find some companions, it is funnier and safer.