When I am free motion quilting on white on white, black on black, or any very busy fabrics I also turn off all lights except for the trouble lights clamped on the ends of my frame. They shadow the quilting well enough that I can see where I have already stitched.

I haven't done matching thread and I hope not to. I agree with you on using a slightly different color so the quilting will show. I had some custom quilting done last year (beyond my capabilities) and she used matching thread. Her quilting was beautiful but you can't see it. I was disappointed with the results. I much prefer the quilting to show. Not a blaring contrast, but a subtle difference in color.

I have always used Hobbs 80/20, Hobbs Polydown or higher loft batting and have never had too much trouble seeing the quilting even when the thread matched perfectly. Recently, however, I did a customer wall hanging and she brought W&N batting, wanted matching thread and the fabric was fairly busy. She wanted custom quilting and I tried every lighting configuration I could think of and still couldn't see what I was doing. I was really disappointed with the final job because you really couldn't see most of the quilting, but she was quite happy with it. She entered it in our local fair last month and won a 2nd place ribbon. I, personally, prefer at least the loft of Hobbs 80/20 and/or a slightly different colored thread, because I like to see the quilting.

My frame is in front of a double window so that in daytime there is lots of bright light. In the evening, I sometimes put a light on the side of the frame.