I use 505, too. It's great stuff.
I did use a fusible batt for a baby quilt once. I didn't like it much, because I couldn't fuse it on my table, where I'd laid it out. I didn't like the fact that part of it hung over the edge of the ironing board while I was working. I like my quilt sandwiches to be perfectly flat when I baste them.
I did pull the ironing board up to a table, to help support the quilt at the back, but really felt uncomfortable with the process. I also didn't like the fact that I couldn't pull the quilt top up and reposition it, the way you can with basting spray.
That said, I have friends who love fusible batting. I guess it's a matter of taste.
Anne in Vancouver, Canada.