I think both the
Migsel and the
Bike-Quip offerings appear to be well made and would serve quite well as a RAM mount base for a GPS, action-cam or other device you might wish to support. Certainly they're a packaged solution with little work on your part other than the installation.
I'm quite happy with the specific options for device orientation that the RBIS affords. Both the Migsel and the Bike-Quip position their RAM balls extending back toward the rider from the dashboard whereas the RBIS places them on top of the dash, forward of its edge.
With a tankbag, and a cellphone mount on my MCL bar riser cover, I already find simply reaching in to turn the ignition key to be more cramped than I'd like. I could imagine that the Migsel and Bike-Quip would be worse than the RBIS in this regard even if you angled the RAM arm away from the rider. I would love for anyone with experience with both styles of mounts to add their opinion in this regard.
I see the pictures on both sites showing a GPS mounted and extended back toward the rider. I find such positioning more difficult to read at a glance with these aging eyeballs that don't focus on nearby objects like they used to. The difference in the distances to the instruments, GPS display and the road make it just that more fatiguing for me. The RBIS let's me position my GPS screen farther away than I think I would be possible with those others.
As for swapping between bikes... The Bike-Quip clearly shows the mounting blocks and screws they use to attach it. You could either order an extra set of blocks and screws from them so you can leave them in place on the bike not currently hosting the mount, or I suspect you could source the M6 screws and barrel nuts yourself for that same purpose. Then you'd semi-permanently be using screws instead of clips to secure the windshield inner cowl to the meter panel.