I did the upgrade on my AxiomAir and it went fine, but now I'm having a couple issues.

1) Axiom air doesn't show up on BubbleUPnP. It does however show up in JRiver.

2) Volume is glitchy. When I try to change volume in JRiver or JRemote the volume mutes. Any changes done in the Axiom app are not reflected in JRiver.

I did my upgrade on a PI3B (purchased with card from Axiom).
I would like to switch a a PI3B+. Can I simply move my SD card over or should I get a fresh card from you guys?

Oh yeah. Bluetooth works well but is very loud. My bluetooth volume is around 3-6 when my wifi volume is around 70 (70 is probably a little higher than typical users because of volume leveling done before audio is sent to AxiomAir).