I use the JT brand all the time and have never had any problems with it. I still have a few spray basted wall hangings from a few years ago on my design wall and they are still holding perfectly while waiting for me to get off my sticky.....
and quilt them!
Very little spray is needed to make the sandwich stick together. I always try a light spray first and then spray a little more if it needs it.
peace
@ Bellaboo: Very cool idea. What a nice DH.