When I was on the fence, the best thing I did was take a class. It was WAY more informative and helpful than the test drives at the shows.
The class was offered by my local Innova dealer. It was 5 hours long. There were 5 of us in the class and we did EVERYTHING. We learned how to thread and operate the bobbin winder. How to load backing, batting, and top on the frame using just about every technique out there, from pinning to zipping to red snappers to magnets. We learned how to operate the head, and the various options/models they had (robotics vs stitch-regulated vs non-regulated). We learned how to adjust tension, both thread and quilt. We learned how to troubleshoot all kinds of issues. How to change feet. How to change needles. Then we practiced, practiced, practiced. Our instructor gave us a lot of samples to see, and try our hand at replicating. She was very helpful! We got to try using various different rulers. We got to swap machines and see what it was like, moving an 18" head vs a 26" head.
The class was aimed at those who wanted to rent time on a longarm, but I took it because I wanted to play with the head more than the 10 minutes or so you get at a show. It was 100% worth the time and money - after I took the class, I felt very comfortable with my decision to buy.