No. If we need to specifically update MySQL, that's going to cause MySQL to bounce. We don't do that often (you can count on your hands the last year the number of times we actually updated MySQL), and with Second Generation you get to choose a maintenance window which we didn't have for First Gen.

What's different is that if we needed to make a change that required only querying MySQL, such as listing your databases in the UI, we would still need to bounce your instance for that functionality to come up with First Gen. With Second Gen we don't need to, so we can add many new features without restarting MySQL. I don't want to speak out of turn lest the lawyercats that come up with SLA numbers and such find me, but I am personally confident that once we exit beta, most customers should generally experience better than the 99.95% uptime we have SLA for First Gen.