My eye and “feel” for leveling the print bed using the paper method is lousy. Misspent youth I suppose… Anyway it seemed to me that since the extruder goes in and out so easily that would be a good way to mount a dial indicator. I modified the STL file for the extruder holder to attach an indicator. See http://www.thingiverse.com/thing:551366 if interested.
Tuns out it wasn’t too awful, about 0.1 mm high in one corner. Now it is within about ±0.02 mm over the whole bed. I’m printing a part that has been kicking my butt for far too long, and it is looking to be the best piece I’ve printed so far. About another three hours to go but well past the point where a corner would start to lift.
BTW, as a relatively new TAZ 4.1 owner, thank you to everyone who posts here–most questions I come up with have already been covered in detail.