Glad to hear it went well and you'll be continuing it monthly. Open it up to audience members, too, me-thinks.
The monthly acoustic blues jam here hardly ever had a drummer. Wasn't needed, but we always welcomed anybody that brought any percussive element. Had a friend who was a great trumpet player, but at acoustic jams would bust out a pizza box and brushes! Better than most snares...
Celtic band, string band ... hardly ever got to play with drummers before, so I always enjoy having a drummer in the mix.
Recently I've played with a punk drummer who self-admittedly had no clue about the blues, which alas is a large portion of the set list in the band I'm currently in... Great guy, good hang, but no blues feel — he also had a tendency to speed up.
Got a blues jam (blues, but other stuff always creeps in) this coming Saturday.