So far, the average-case timings I have are:

15 minutes - mysqldump
5 minutes - transfer
15 minutes - mysql import

Plus another 20 minutes for hardware fiddling. I think 2 hours is a reasonable window to expect

Here's some performance graphs before and after the upgrade.


This is the old DB server's typical load over a day. Look at the fat IO Wait graph, indicating that we're IO-saturated.


While this is the new DB server's typical load. What load!?


And as a consequence of reduced DB backlog, the webserver's load spikes have reduced as well. This is a weekly graph, so compare the first 3 days (pre-upgrade) and the days following it.