For instance, with a terminal program? How hard did/do you find it on your eyes? It's difficult for me to judge how bad it really is via emulation. Is the 60Hz refresh of NTSC noticeably more comfortable than PAL's 50Hz (for those who have experienced both)?
What if the content is in motion? When an interlaced display is scrolling or otherwise animated to keep the eyes moving, does that reduce the strain? Are there any interlaced games for the C128?
I used Zed 0.77 with the C128 in 80-column mode and with Zed's 50 lines per screen (interlaced mode). It was tolerable, because I used the Sears LX1 television/composite/RGB monitor which had a 20-inch screen.