I like the idea. Well, at least the theory of it.
My concern is that, in practice, I will spend the week before the conference working on the talks and will, by Saturday, be so exhausted and looking forward to sleep, that I wouldn’t be very efficient the week after. So, if it wasn’t for the travel expenses, I’d rather completely decouple the “sprints” from the conference and only meet for one day before the conference for a team warm-up. To me, the conference is kind of the peak of all efforts during the year, and when that is reached, I really need time to recover.
So, how about shortening the “sprint” to 1-2 days, and always focus on vision / warmup. We could do a retro, could do some fun event so everyone catches up with the spirit. But no serious coding or trying to get a release done. And then have sprints independently from the conference.