I have two straight stitch only machines (all I need) with 9" throats and I mainly do FMQ, a large meander or large stipple and they both have plenty of room. I have made large ones but, mainly double size.
Buy the one you can afford and you will be happier with it.

It would probably okay for piecing but not for quilting the pieced top.

I completely agree. I am new to quilting, but I know that if I had not gotten the machine I did (by making monthly payments), I would have given up long ago. Do all possible to get a good machine!

I have a pfaff 4.2. It has a bigger throat space for quilting and allows you to have a bunch of bells and whistles. I love mine.

Before you buy, think about what you want to do with it - piecing-type quilting or using embroidery features. If plain piecing-type then you have a lot of options. I do my piecing on a 14-year-old Bernina 140 Patchwork or a Bernina 230. These are basic Berninas. When I do the quilting I use the 140 because it has a 9" throat. So, if piecing is what you are looking for and not "bells and whistles", check out used machines. Whatever you get, make sure you clean and oil it before you start any project. Practice on scraps to get used to the tension and get comfortable with it. I also get mine professionally cleaned once a year. That's expensive, yes, but I have never had anything break on these machines. Also, when free-motion quilting many of your problems may not be related to the machine but your surroundings. My machine sits down into a sewing table. When I free-motion quilt I pull my table into the middle of my sewng room, put a folding table at the back and another at the left side. That means all of my quilt is pretty level with the throat plate and I can move the quilt easily. Less stress on the sewing machine means good stitches. Good luck!

throat space
 

I will admit, I am AWFUL at quilting with my sewing machine, so the smallest throat space I want to work with is 18"...which is why I bought a longarm 9 months after I pieced my first quilt. If I was restricted to a sewing machine, every quilt would be a quilt as you go! I love my Innova longarm and it was actually less expensive then some of the Berninas out there.

100% agree!

My used HQ16 paid for itself and I don't quilt for money. If I had to send every quilt top that I make out to be long-armed, I'd be broke.

Check out the class on Craftsy - Quilting large projects on a small machine (or something like that). I believe Ann Peterson is the instructor and she is fabulous. She shows how to maneuver the large quilt sandwich in the machine and her machine does not have a large throat.

Janome 7700 has 11 inches. It's great.

I started with a Brother HS-2000 and it has a very tiny throat area. I researched for a year, then bought a Laura Ashley, special edition, Innov-is, NX-2000 which was built for quilters. I quilt all my own quilts and this year have been working on a lot of queen sized quilts. I adore my new machine & would not trade it! It comes with everything you could possibly need for quilting, such as walking foot, darning foot and 15 others! Good luck with your research!