I think 100Hz TVs were a Euro thing, or at least a thing for countries that have 50 Hz mains.
100Hz did (in the end) do a proper job of hiding the bad flickering that is caused by the low refresh rate of the pictures. The first 100Hz TV's however had bad problems when large things were moving on screen (or when panning the camera etc.). I hated it and waited long to get a 100Hz. Only when it was mature enough to handle this kind of data. I still have a 16:9 CRT TV, and I will keep it for as long as it will run.
I still prefer a tube. Nothing beats a tube. yet.
Anyway, in the US (and other countries using 60Hz.) this was less of an issue for 2 reasons:
1) 60 Hz gives a steadier picture
2) hardly any 16:9 TV's
And here's an important point: most of the classic arcade games run at 60 Hz. This combined with the fact that most classics have a black background will give a steady picture on a 50Hz TV/monitor too. No need to worry about the 50/60Hz. any TV that is at least a bit modern can handle the 60Hz. signal (f.i. the TV I used for my Galaxian cab is about 13 years old and has no problem with it.
I would always prefer the authentic look of a CRT. But that's all personal taste.
Ok, so my 28" monitor/TV-thing should handle running at 60 Hz, i guess that makes sense (but with a lower resolution maybe?). I think it can handle both NTSC and PAL-signals too. (when i ran it with TV-out i even used 800*600). The fact that the games themself run at 60 hz isn't really that important for me I think, the reason for 100 Hz is less flicker, and nothing more (for me). Is there a way to check what refresh-rates and resolutions the TV can handle in a reasonably reliable way? Maybe 60 Hz would be ok, but I think i react stronger to flicker when I'm closer to the monitor, and in a cabinett the distance probably would be no more than 1 meter.
When it comes to the "scanline-test", I prefer running without scanlines on my LCD-monitor. But I always find scanlines to be more "intruding" when added artifically. On a "real" tv its more blurred, and less noticable, so it's not so bad too look at.
AtW
If I were you I'd definitly use that Sony. Resolution will not be different in 50 or 60Hz, there's no relation. If it can handle NTSC than you're fine for sure, but the TV system is not of importance when using it as a monitor for RGB signals. NTSC and PAL are merely ways to "encode" and "decode" TV signals so they can be transmitted through the air.
Because the games (most of the classics) run at 60 Hz. you won't really need 100Hz. In 60 Hz., the picture is already much more stable, simply because there are 5 more pictures drawn per second (10/2 because TV's interlace). That may not sound like a lot, but it's enough for our eye.
The eye needs about 24 pictures per second to let it seem real. When you've got a 50Hz signal, you get 50 Half-pictures = 25 full pictures. On film, this looks very stable because you get to see the complete image at once. With a CRT, the picture is drawn dot-by-dot, which gives it more flicker.
(If you want to check this, find a 50 Hz. TV and instead of looking straight at it, look at it in the corner of your eye.(so get your face at an angle with the TV and look straight ahead where the TV is not. Now, you should notice the flickering much more clearly then when you look straight at it. That's because the edges of our eyes are more "focussed" on moving things than the center. That's from the times we had to run from things like lions, but it's still handy when crossing the street now....)
Anyway......the thing I always remembered from playing arcade games in the early 80's was that I was so amazed by the great picture quality. We didn't have any RGB playback devices then (except the Laserdisc, but who owned a Laserdisc in Europe ?) so I thought the quality was so good looking AND stable. I only found out the reason why years and years later (the games running at 60 Hz.) All TV's were 50 Hz. then.
I've got a 25" monitor in my Jamma cab. It looks absolutely fine when running the games. Of course it sucks for displaying windows, but that's only normal. So if the classics are your goal, you'll be fine with the Sony.