akhullar, the CTO was not able to help (and I got a great, helpful TA with 25 years of DL experience who spent 40 minutes trying to accommodate me). But she said she couldn't imagine the upgrade not clearing with 30 seats open as of today. You seem to share that view. So I'm going to take a chance and purchase the tickets. Thanks!
Once again, though, you've got to love those front-line DL people!
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Vasant