I have found that spray basting helps prevents puckers.
HOWEVER, in my experience what helps prevent puckers even more is heavily starching the backing fabric before layering, and spray starching the top before layering. For the backing fabric, I use a 1:1 solution of Sta-Flo liquid laundry starch and water, "paint" this solution on the fabric to saturation, toss in dryer, and iron with steam. Believe me, that fabric is *not* going to stretch or distort while machine quilting! :-D
Spray starching the stop helps keep the top fabrics from stretching. This is especially important when doing cross-hatch type machine quilting where lines will cross.
Just be aware that some combinations of starched fabric/polyester batting/spray baste do not hold together well. I have not had any problem using 100% cotton batting and 505 basting spray, even with heavy starch. Some people have reported problems with spray basting adhering to starched fabrics and/or poly batting; however, I think in all these cases it was other than 505 basting spray.
Edit: I should add that I never stretch my backing or top. If spray basting, it's enough to make sure it is laid out smoothly. I do use clamps to keep the backing from moving out of position while I baste. Be aware that there are techniques for spray basting that make the process very easy and minimize overspray and cleanup. But that is the topic for another thread!