I've had a Vive since last week, just sold my DK2 a couple of weeks ago and like Mad Mike, I am in the 23rd May - 2nd June and just hoping I get my Rift sooner too.
I intend to keep both, and use the Rift for seated and the Vive for room scale. I was thinking of selling one of them when I first pre-ordered, but I think there's enough experiences and preferences to keep them both.
What I care about more is not having titles locked to a headset, and for me the Rift puts me off slightly that if the AAA titles come to the Oculus Store, they won't work outside of the Rift, or indeed outside of that Store. Whereas whilst i know Steam is also a store, Valve just want to sell the games and therefore support all headsets (provided the titles themselves do). Therefore, the Vive is more flexible in that regard being SteamVR which is open.
I've also found the standing / room scale experiences very engaging- even something simple in terms of design like Audioshield is great fun, and the haptic feedback from the controllers adds another layer to it.
And whilst I've got an extension coming to accommodate a 4mx5m setup of room scale, for another month until it's finished I've only got 1mx1m spare room, but plenty of titles are still capable of working in a standing position and just the room to put you arms fully out and around you.
For ED, the Vive tracks okay for me with just one lighthouse in the sitting position, and is perfectly usable in terms of quality until Frontier hopefully improve it to match the recent Rift update, as the demos at EGX last year looked much better than the current implementation does on the Vive.
I think overall for anyone who's feeling agnostic there are pros and cons to both, but for those potty enough (like me) to get both then there's benefits to having both if you really love VR (like me)!
