The speed thing would be an issue for you for all of about 15 minutes. I've had so many people use my machine, even children, and they get used to it very quickly. You get a feel for the pedal and can go slow, a stitch at a time, or fast, 1500 stitches per minute. I know it seems counter intuitive, but it really is easier to get smoother quilting lines the faster you go. All it takes is practice...
Even if you don't go for the Juki, still check out some of the other semi-industrial straight stitch machines - you would never look back! I really really recommend getting a machine with a knee lift. It was life-changing to me! You never ever need to lift the foot by hand which is HUGE when you are machine quilting. And the automatic thread cutter is something I can't go without now either. And I don't mean a button on the machine - it's on the foot pedal, so you tap your foot. When you are quilting (and piecing!) the more your hands can stay free, the better.
...I think the people who benefit most from Berninas are those doing beautiful heirloom sewing. People who actually use all those lovely stitches...If you think you will, then great! If not, you need to get the best quality machine you can get with the LEAST amount of stitches! For me, that is one, the straight stitch. I think a zig zag would be nice, but honestly, I have never needed to use it bad enough in the last 4 years to pull my Janome out of the garage!
Also, you are not going to want to keep the same machine forever. Our mothers did because all they did was make clothes in the 70's. I remember! They weren't making works of art like quilts. Quilts require different things than clothing...
If you want to quilt your own quilts, and they are bigger than a yard square, you NEED an amazing dedicated quilting machine. So here is my list of what you should look for, regardless of the brand. They are things that in my humble opinion are the only things you need for quilting:
Big throat space
Big flat bed
Automatic thread cutting
Easy to lower feed dogs (flick of a switch)
So there you have it, from a truly amazing quilter who has really put her machine to the test! I thought about what she said and even found a dealer in this area (Reliable Sewing Machines in Stoughton).