I also purchased my first long arm when I was an intermediate quilter. A couple of things I didn't know:
-The frame is also pretty important. Make sure you get one with sturdy bars. My first machine had rollers that were slightly flexible. You couldn't rest your arms on them to steady yourself for detailed work, and because they were slightly bowed, it affected the tension on the quilt sandwich. Also, a dead bar makes life much simpler.
- You need a lot of room. Figure on at least 3 feet in front of the frame. If you are planning on doing pantos, you need 2 - 3 feet in back. You also need a couple of feet on the side where you will be advancing the quilt, and if your frame doesn't have a dead bar, you will also need access on the other side. remember too that the carriage the machine rides on takes up about a foot of room, so a 10' frame gives you about 9' of quilting space.
Although my first long arm wasn't my dream machine, I still really enjoyed the stand up long arm process. I eventually traded up to my current model.
I would also advise you to do some research in your area to see if you can rent time on any machines. This will give you a realistic take on the long arm experience.
I would also go to a national show and try all the machines.
Finally, ongoing dealer support is essential.