Randy,
decent observation, I to have noted some issues with tape adhesion on metallic colors. However most of the time I believe its because there is more texture on metallics than there is on straight colors. Personally I ALWAYS shoot a coat of clear over metallics before masking. I have had lots of issues with tapes adhesive creating discoloration on the metallic particles. Not so much these days with modern materials, but just the same,,,,,,
a couple things to add to your list of "do this on difficult situations",, make sure your tape is as fresh as possible especially on known difficult situations, as you can relate, 8 $ for a new roll of tape is easily worth it compared to  remasking a complex design. I try to keep my good fineline, and other masking tape sealed in a ziplock bag so that the adhesive doesnt dry out, this helps, also keep it out of dust,, (duh!) and out of the sun. When masking tighter radius corners, I usually "pull " the corner once to prestretch the tape, then lift it and relay it so that it doesnt have as much tension on it. after its masked I immediatly go back on the inside of the radius ( actually that is somewhat decieving, lay the 1/4" crepe on the side that isnt getting painted, regardless of which way the radius goes)and lay a track of 1/4 crepe tape along it, this will help stabilize the stretch so it is less likely to pull. Of course keep the temp as stable as possible once its masked until you actually spray it, if you turn the heater off overnight the temp change is an invitation for problems.


Just some thoughts, hope ya dont mind,, looking forward to seeing the new beast!

I have some old mole traps that need painting. They were gold, probably to attract the females. What techniques and materials would you suggest?      Steve