yamaha cp 70

I used to play one in the early 80s and had 2-3 gigs a week. It often rode in the back of a van both ways, the trips being maybe 10-30 miles each way. Both pieces were usually stacked on end on the bare metal floor, so they sometimes took some serious knocking around.

The tuning held up remarkably well. Of course there's no sound board, so changes in humidity were not much of an issue. I would tune it at the point where I felt it was no longer just chorusy, but starting to sound obviously out of tune. Average once every 2-3 weeks.