I use the 505 and it seems to be well worth the additional cost over the Sullivan's. You can use it sparingly, so a little goes a long way for me. I would never, never, never, never use Aqua Net...why would you spend all that time and money making a quilt and then not spend a couple of bucks to get a quality spray baste and possible ruin the quilt? Doesn't make sense to me, but thats just MHO..
But, try spray basting, I think you will find that you love the option!