Buying a LA is like buying a car - what works for you may not work well for someone else, and vice-versa.
This is a large investment. Take the time, spend the money, and go to one of the large shows. Most if not all the machines are represented. Take your time and play on them ALL. Machine Quilters Exposition - MQX (in the North East), MQS (Kansas City), Houston, Innovations (Tacoma WA), Quilting with Machines (Salt Lake City), Portland....well, you get the picture. There are shows all over and I'm sure I didn't hit them all.
Most of all - have fun!