I don't think that polyester spot putty is any real issue here. I used it and it showed no signs of becoming unbonded and besides 95 percent of it should end up on your shop floor anyhow after you've done your sand out. Just a note here, there is a product called Feather Fill that was all the rage in the 80's and early 90's that is a sprayable polyester high build primer. There are probably a couple thousand KR's, VariEze's,Longeze's Quickies, Dragonfly's etc.that used this product. Maybe I'm not in the information loop but I haven't heard of any problems.
