If Halo had a good JiP system, it could be of great benefit. Nothing pissed me off more way back when than when I was playing a good game of team slayer, having a good time, when 3 people on the other team quit. Halo then turns into a game of hide and seek. And it's boring as hell.
4's JiP could use a lot of work, but I can't even think of a super fair system at the moment. Maybe like mentioned before where JiP won't throw you into a match unless theres more than a certain amount of time left.
Royal with Cheese. What do they call a Big Mac? Big Mac's a Big Mac, but they call it Le Big Mac.
I love JIP. This is probably because I was on the wrong end of many mass quitting/lagout events throughout 3 and Reach. It sucks being the only guy left on my team, with 8 people constantly hunting me down and spawnkilling. It caused me to stop playing Invasion unless I had a full team of friends. JIP solves this problem unless, of course, we're put into a lopsided game or one that's about to end. People have already pointed out that JIP should only put you into games that have a good amount of time left. However, I have joined losing games and come back to win plenty of times. Strangely, there's some glitch where you can't JIP on DLC maps most of the time.
"The most important thing is to never stop questioning." -Albert Einstein. Xbox Live: AlteraLateralus