Back in the day, I used to be able to play Gauntlet, Punchout, and Joust forever. After the first 10 million on Joust I didn't really feel I was proving very much.(posted 9286 days ago)But the spirit of MARP seems to be to include everything, what with the clones of Dig Dug and all. So I guess the best thing to do is have both. Twin Galaxies does track scores for marathon and tournament for a lot of games, but think if you had a Qbert tournament and it was on factory, it really wouldn't prove who was the best player, just who could stay awake the longest.
Personally I wouldn't really want to go for the Marathon Joust world record... It's over 67.5 hours. That has to be bad for your health, plus I'm over 30 now, and I don't have the luxury of playing Joust for 3 days (I really doubt anyone here has that much free time).
It is good practise though.
As for the Qbert 5 men rule, all you need for that to work is a version of MAME with a death counter on screen, which would be easy to make. Then once it hits 5 then player can see they are finished.
I'd add that to my list of things to do... ;-)