I had my 210E for a while and thanks to this thread, made mods on the AC/DC order at power on, 6000 count, 4hour auto power off, unlimited backlight, NCV in mV.
I wanted a second unit but it was not available locally so I got myself a 210D instead and also decided to do most of the same mods. Worked just as well! There were some little differences in the function addresses so I did not mess with them much, I just changed the DCV, ACV order, added mV function on the AC volts, 6000 count, auto shut off and backlight timers.
I also run my 210E with a li ion 10440 cell via a 3.3V LDO. Lasts quite a while and backlight is a bit brighter, beep is a little louder too.