sounds pretty instant to me. As others have said, no different than my Mesa or my Voodoo amps channel switching.
The Keystone DSPs (that I'm aware of) have a pretty wicked ethernet co-processor with all the bells and whistles. They have native 10Gb and a full security and packet processor onboard. I wonder if the Fractal folks will ever be exposing that to the world? Wouldn't it be awesome to have a AFIII on the network to sync presets, load IRs, and expose loads of automation, etc etc? Maybe even send audio over ethernet instead of pulling USB cables?
It's worth noting that the product is 30+ days from shipping, and the Axe III forum already has 3 pages of threads. Mania.
And I predict the waitlist will be populated for a good solid year...unless FAS has a the factories on war footing for this initial surge.