Yes --- testing all the machines is important. What feels good to another may not feel good for you.
The amount of room you have for one is important. A Gammill is much bigger than a HQ Avante.
My biggest suggestion for everyone is to look for a LOCAL (or closest) dealer. I was babysitting a machine for a friend and the nearest repairman/tech support/trainer was a 400 mile round trip. And, of course, they wouldn't consider any training. My friend also had the same problem.....Regardless of how good the machine is ---- you WILL need help. Find out if the store will provide one-on-one training or have classes.
Good luck and HAVE FUN!