dbh wrote:If I had access to a Mac, I could test that theory out

I was actually thinking of getting a Mac so that I could watch Mac MARP recordings. Any suggestions for a low-end Mac suitable for watching/playing MAME on?
For watching...any G3 or better will do...cuz speed doesn't matter much for watching. For most games you can alter the frameskip on playback and it doesn't affect the playback to get the speed.
However, playing is another story.
First, be aware the last few versions of the official macmame are for OS X only. If you got an older mac with only OS 9 on it you wouldn't be able to view replays using these latest versions of macmame. 0.66.2.x is the latest official version for OS X. However, there is an unofficial version put out by a japanese group that does also run in OS 9. I have used that version from time to time cuz they are fast to release new versions where the official takes a bit. In every case replay files made with the unofficial one playback fine in the official one...so likely no issue going the other way also.
The new official macmame has a great new integrated opengl renderer optimized for OS X that works very well. The unofficial one doesn't have this...since it's made to run in both OS X and OS 9.
I play macmame on a 450MHz G3. For most of the golden era classics, I can play them at 100% without using any frameskip. For others like Marble Madness or Gauntlet etc., I need to use a frameskip of 6.
It depends on the budget you set for buying the mac. Through eBay you can get some macs pretty cheap....others are pricy. It varies.
If you seriously wanted to play most games using a mac then I would recommend something more along the lines of a 800+Mhz G4. The cheapest mac along these lines is actually likely an eMac...which even new is only like $700 and is an all-in-one type unit....display and CPU etc. all in 1 casing. You can get details on that at the Apple store if interested.
You likely can find some used/refurbished towers of similar speed for what likely would end up being about the same price.
I would just check eBay to get what market values are for used and older macs.
My 450Mhz G3 does me pretty good for most games I want to play so perhaps something along the lines of a 500Mhz G4 would be enough for what you would want to play.
I hope that helps. Think of it similar to PCs. Think of what you can play on a 600-700Mhz Pentium system....that would be fairly similar to how a 500Mhz G4 would be. If getting one with OS X, for it to run pretty well; you will want to have at least 384 and perhaps 512 meg of RAM in it. One with OS 9, 192 or 256 meg would be plenty.