Using the check and repair functionality for server storage has a known issue logged against it which can result in data loss. I haven't been able to recreate that issue, but I haven't tried very hard. From your bug on Connect, it sounds like you've
hit this issue, for which I'm sorry even though I'm not a Microsoft employee, only a Windows Home Server enthusiast. (Note: removing a "missing" disk from server storage also has a known issue against it, which will result in data loss.
I have tested that one, and it's not pretty.)
As for recovering your data without Vail, there is no way to do so at this time. Disks that are part of a Vail server storage disk set are only readable via Vail.
I'm not on the WHS team, I just post a lot. :)