I have heard that bondo dont stick to epoxy primer. 

I've never had any issues. 

I keep hearing references to this "Bondo" -- What is that exactly?   Some kind of Polyester filler/primer?

I use cheap polyester filler on a lot of my patterns, I've never had any problems with mixing it with Epoxy .. As long as it is allowed to cure for at least 24 hours .

I often make patterns out of cheap floor insulation foam .. it will "melt" when in contact with the EC pattern primer, so I "seal it" with a layer of epoxy, leave it to cure for 24 hours, key it with 120 grit, then use polyester filler and EC pattern Coat primer -  If I accidentally sand all the way through to the foam, I just re-seal it with epoxy, then carry on with the Pattern Coat primer ..

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Bondo is just a brand (the original brand I believe) of polyester body filler. 

A polyester will stick to an epoxy a lot better than a epoxy will stick to a polyester even thou the epoxy is stronger

Never had any problems but surface prep is important

youll be fine. Ive often had to fix little spots after I have sanded the primer and the guide coat showed the low spot. Make sure the primer is rough sanded so it has a bite for the filler to stick to

When I first got into this game 82/83 ish pre preg had only been out (or I should say in use in f1) for a couple of years

there was a split between pre preg (floors,rear flips ect) wet lay epoxy vac (endplates,elements ect) and polyester hand lay glass (brake ducts,bodywork ect)

ALL repairs were polyester and the guys who were there had been with lotus cars/moonraker marine/jcl from early 60,s an that's what I was told

never saw any repairs delam

If they were with Lotus then I don't believe a word they said, their panels are the worst I've worked on!