I have had some problems with the spray adhesive being in places I don't want it to be, so I find you have to be very sparing when you spray it. I like your idea of spraying (sparingly!!!!) AND using pins. I think I'll try that next time.
I have been doing quite a bit of long arm quilting (my LQS has a program where you can rent their machine, after taking an instruction class, for either 1/2 day or full day, and I love doing that), but one can't always afford to do it that way.