About the build-up...
I have seen mixed behavior there. When using a fresh bottle of flat paint, like Black Oxide or Coyote Brown, properly sprayed, I have had no problems with the thickness of the product. OTOH, the glossier colors I have tried run thicker.
Once I tried to use a bottle of Electric Cherry over a White base coat and it went on like truck bed-liner. (Well, comparatively.) That may have been due to the fact that it had been sitting on my shelf for a while, and I didn't get it straight from Lauer - who knows how long the retailer had it. Per the FAQ, "The shelf life of DuraCoat hardener is 6 months." Don't waste your time with old hardener.
Oh, and if you need to remove DuraCoat, I highly recommend Zip-Strip (original formula). I have never had a problem with DuraCoat coming off of decently prepared surfaces, but 45 minutes soaking in Zip-Strip and 90% of it literally slid off without being touched. A light touch with an old toothbrush and some Q-Tips did for the rest in a couple of minutes.