I think it has been hinted that it would just be a normal (routine) upgrade, other than that the download and time to complete will be substantial. You won’t know for sure until it happens.
A decision between A and B depends on your level of expertise to resolve problems when they arise and whether your use of the computer will tolerate the disruption of putting your time towards doing so. If it were me, I would go Amber - and that’s not just because of the recent specific problem with gnome shell.
You can never have too many computers though. 
So if you really want to play with the latest version of package X then have the best of both worlds - one stable and one rolling. When rolling is broken you can at least fall back on stable. Maybe you can do this via VMs.