Buy what you like and want not what a dealer or someone tells you to buy. If you are going to go high end, I would spend several month looking at different machines. Go to shows and try different brands out. For me I drooled over my machine for 2 years, but couldn't afford it. I went in to actually price lower models to upgrade from my cheapo mechanical brother. When I went in they told me their payment plans and I opted for my dream machine the babylock espire (symphony and ashleys predecessor). I would say it was about 6 months before I was completely comfortable with my new machine. It was easy to use, but has many many features. To this day almost 3 years later I still learn new things about her. I love all her bells and whistles, and miss them when I sew on my lower models. You don't need these features but they are nice to have you will only know if that is what you want in a machine. I would say start small and work you way up. my first machine was very basic mechanical brother with limited stitching, then I got a mechanical with more features. Now I have my baby, and upgraded my small mechanical brother to a small computerized one from walmart and can say I love my little one even though she doesn't have all the features of my big one I can do almost everything on her and she is so portable. I would if I were you get a smaller machine with those features and see if FMQ is something you truly enjoy before shedding out the dollars for a big machine. You can FMQ wall hangings and lap sizes on the cheaper machines, and even with a decent harp you will still have to get the hang of maneuvering your quilt. Some don't like it and opt for a mid arm machine to do it and a small machine for piecing. I paid 109 for my cheap mechanical brother 7 years ago and it does everything you would need it to with out the big spending.
Some of the features on the high end machines that make them nice are
automatic thread cutter
ability to adjust presser foot pressure, and height
pivoting feature with automatic presser foot lift when foot is released from pedal
knee lift for presser foot
needle down
screed instructions on basic threading of your machine without pulling out manual
bobbin winding independent from sewing function
low bobbin detector (no more sewing for minutes with no bobbin thread)
automatic tension adjuster
memory pockets for saved stitches
stitch length and width adjusting abilities( width was not an option in my first machine)
drop feed dog capabilities (these are only on my computerized machines)
My computerized small machine has drop feed and needle down feature so that it is more features for quilting than my second mechanical machine and only cost 200 ( 180 with the rebate) has blanket and decorative stitches and many feet that you would need for garment sewing without braking the bank.
Honestly I have practiced FMQ and the espire is just short of 9" harp, and don't know if I would do a big queen or king on it ever.