Picked my new XR 529 with ei shock on the weekend. Had it out for a decent 4hr ride. What a great bike! Much much quicker through singletrack than my Anthem X 0 29er. Climbing is really awesome, although once it gets very steep the bike requires a bit more weight forward compared to the Anthem. It's a lot more stable than I thought it would be on fast fireroad descents as well, not twitchy.
The ei shock: yes it does work indeed; locks out the shock whenever you need to put the power down. Even moderate speed cruising it hardens up which is great. Allows me to run more sag than I would usually, plus I don't have to mess about with the shock through the ride. To be honest, I was quite surprised by how well that part of the bike performed. Of course, longevity of a system like this is going to be the critical test.
Will be weight shedding over the next month. Its not super light yet, without pedals but with the ei shock and battery it was 12.25. Stans crest wheelset, carbon bar and seatpost and some lighter ATAC pedals (compared to XT trails) should get it down to a more reasonable level for enduros, marathons etc.