I just recently started using basting spray. I like it, but I still use pins, but not as many. I just don't trust it yet to hold well enough to keep up when I'm scrunching and pulling my quilt around for FMQ.
I do like it for small projects though.
I saw on a "Sewing with Nancy" video that she used fusible web for a quilt. Make a long thin *1/4" or so strip of fusible, then put at piece down every 5-6" or so and cut it off so only about 1/2" goes down.. Just use your iron on it and pull the extra tape against the edge to break it off. Then when you're ready to add the top, peal the paper off the tabs, and place your top on. Spot iron over the tabs and it holds as well as pinning.
Here's the link
http://www.wpt.org/sewingwithnancy/sewing.cfm
Advance it to the "letter Q" for the technique.
Oops, sorry, Q was on last week, but it's gone now. Or you can order her book.