Well, "bigger" and "smaller" are of course, relative terms.
I'm not a real big fan of baits bigger than 11 or 12 inches, so to me, a 6 o 7 inch bait is "bigger" but not biggest. Smaller is 4 or 5 inches, and those can produce muskies for me sometimes when nothing else will.
So, generally I use 1/8 Lexan on baits over 5 inches long and 1/16 on baits smaller than that.
Occasionally, I'll use 1/16 on 5 to 7 inch baits in an attempt to get a sharp, tight vibration out of the bait even at the risk of having a lip break.
To date, I've never had a single lip break, or an hook-hanger or line tie fail on any of the baits I've built and I do NOT baby them when I'm trolling. In fact, I am a big fan of bouncing crank baits off rocks and point edges hoping to trigger a strike.
As to the quality of the polycarbonate, I have one local source for Lexan and its all I use, so I really don't know about what else is out there or how it performs.