[sciurius]

I imagine you can simply get the separation with the name of the group in the setlist and a persistent or favourite filter as well.

Yes, although I would like to avoid the burden of adding the group name to each and every setlist.

Also, before a gig I want to transfer all songs for this group to my phone, just in case. The phone is not capable of holding the complete database with all songs. Note that just the setlist (.msf file) is not sufficient, since there may be last minute changes so I need all songs (for this group) on the phone.

I won't say that separate databases is a necessity, but it certain has a number of interesting benefits.