The time periods I refer to are the one 50th and one 60th of a second timing for the fields for PAL and NTSC respectively.
Re-reading the post, I must've got you wrong here (think I read "PAL is
less flickery here").
However, I still don't follow you on the "physical height" of the pixel. Sure, PAL has a higher resolution, but on a CRT, a scan line drawn is always the same height and covers the same area. On PAL there are more lines (tighter spacing) than on (full frame) NTSC, so the pic appears slightly brighter - which means more contrast & more flicker.
On an LCD it's another story, but then again - that's a progressive display and shouldn't be flickering at all.