I personally like custom LCDs. They are very readable and look somewhat "classy" compared to graphic LCDs/OLEDs. No ugly pixelated icons and digits. Of course they are a lot less flexible, but that's also a plus in some cases, as it naturally forces the development to avoid bloated UIs and such, and keep the probability of display bugs much lower.
As to e-paper displays, I don't think that would be a good idea at all. They are terrible regarding refresh rates and the refresh process itself looks ugly. On more recent e-paper displays, you can do partial updates which admittedly are much better looking but that still doesn't look too good when the display is changing fast and constantly. Besides, they actually draw a lot more current than simple LCDs if you refresh them constantly. They are optimal for very infrequent changes. Also, they are pretty expensive if you want a decent resolution (and the small ones with low-res, they look ugly IMO - that's good for price tags but not much else).
I don't know whether Dave plans on adding a backlight or not. Not sure that would add a lot of value. Lab areas are usually well lit, so unless he wanted to target geeks working in their basement with dim lighting....
(a backlight could prove useful on a portable multimeter if anything, but on a power supply...?)
The only thing to consider IMO would be glare (that could be annoying depending on how your lighting is set up) so if an anti-glare coating is possible (either directly on the LCD glass or as an additional front filter, that would be a plus.