Body filler

I just used some new (to me, anyway) stuff. I think it is made by Bond-o, but it is lightweight gold filler. Went on very smooth, good for thin coats. I couldn't believe how light it was, felt like 1/2 the weight of the old gray stuff I always used. A friend of mine (who is a body man) suggested putting a few drops of fiberglass resin in the stuff and mix it up with the hardner. I didn't get to try it, but I will on the next project. Anybody ever done that? How'd it work?