i just chronometered
it took about 1min25sec to boot from usb drive on (i used a USB3.1 64GB Sandisk USB drive Sandisk Ultra fit newest version)
compared to under 30 sec with a Sandisk Ultra micro sd card
It can take a while to transfer roms through ethernet I think it's easier to manage my roms library from usb drive. That's not really the subject here so I won't develop
that's a good thing to know that a internal version of recalbox works with R3B+
I'm building a second bartop and I'd like to use the new raspberry pi 3B+
it's quite irrelevant to install recalbox from scratch since you always advised to use usb drive to store roms, of course it takes longer to load but I think it's worth the wait at every boot: I can manage my roms on a usb drive directly (adding and more often deleting titles from a full set, I know I should own the originals and so on)
I tried retropie since the beta is compatible with P3B+ and to my humble opinion although it's really nice to be able to set every thing, I really appreciate the simplicity of recalbox
Thanks for your efforts guys, I'm looking forward to installing recalbox on a new R3B+