Thanks for the responses.
johnpaint and chrisn, as for the Bondo wood product which we have a lot of experience with, it dries hard as a rock and is workable, but does NOT have good flexible properties where there is expansion and contraction of the wood. It definitely will crack in those applications. Another product similar to the wood Bondo is the MinWax High Performance Wood Filler, also a 2 part epoxy filler, but also not good in applications of contraction and expansion.
As for the DAP DryDex, which we have also used, same problem - easy to work with but NOT recommended for areas of contraction and expansion and my experience here is the same - it will crack (I'm not talking about using this for larger holes and cracks; we use the 2 part epoxy for those).
msargent, I've never used Abatron, but I believe their WoodEpox and LiquidWood are similar to the Advanced Repair Technology Flex-Tec HV that we are currently using.
We use the Flex-Tec HV (featured on This Old House) because of its excellent qualities and could also use it for the small holes and cracks, but we are looking for something with the same qualities but without the 12-24 hour cure time and something that can be applied over primer if necessary. Flex-Tec is to be applied directly to the wood. My experience is that after filling all the holes, cracks, and repairing major wood damage and then applying a coat of primer, we inevitably find other small holes, divots, cracks, etc. that need to be filled.
Does anyone have any experience with Crawfords Painters Putty or Synko Exterior Spackling paste on exterior wood in expansion/contraction environments?
Also, just a quick comment with respect to "better quality painters". I've been a GC for a long time and my experience with "quality" based trades persons is always a battle. People who take pride in their work and profession are definitely in the minority, not considering the issue of experience. I would say less than 10% really take pride in their work. Most are living pay check to pay check and thier motivation is money and not the work. The addage that you get what you pay for certainly applies here. My experience with painters is that they tend be a bit on the hard headed side -- they've been doing things in a particular way for a long time and they have a lot of trouble "listening" to the job specs and requirements. Now that being said, I do find and work with great trades people and companies. They're just in the minority.