product that just wasn't absolutely rock solid.
I no longer work there, but last I heard those financial services customers were much more interested in KVM than they ever were in Xen.
This doesn't really make much sense, as it goes against the conventional wisdom of software development - newly written or younger software by default scores worse on the stability front compared to old software, even if old software was known to be buggy - exactly because of the simple fact that someone somewhere already dealt with many of its quirks, and hopefully put it in order, whereas there is inherently less proof that anyone ever did that with novelty software. There are exceptions, obviously, but I don't think it's common among people who want rock-solid stability to be betting on getting such an exception.