I bit the bullet and did the move yesterday:
Added the Bridge Pro in the Hue app, migrated everything over to that and decommissioned the old Bridge. All lights and devices moved over more or less fine, but only some of them retained their settings; others were the wrong colour and brightness, so they had to be tweaked back to their previous settings.
Then uninstalled the Hue app on my Homey Pro, and installed the test Hue app, and added all my Hue devices back: loads of lights, a couple of plugs and a couple of buttons. All appeared fine in Homey, but I had to put them all back into their rooms.
Flows all showed cards missing so I had to rebuild all of my flows involving Homey devices, which was a slightly tiresome couple of hours. All working fine now, and I was braced for some faff, but it definitely was a bit of a faff to rebuild everything.
