I've only seen 1 person score 10, and of course that was with the disk. He was also the host while everyone else had 300+ ping so that probably helped. :p Most games end with the highest score being around 3-5, as most players fail to make a single kill when playing as the Predator. I think my personal best so far has been 6, which used a combination of all weapons.
The problem is that 2 marines working together are more than a match for a Predator, especially if they're using the smartgun or sniper rifle. If 2 marines are capable of taking on a Predator, then imagine how easy it is for the marines when a full server teams up and works together. The time limit doesn't help, since you're forced to pick up weapons (giving away your location) and forced to attack when it's not favourable.
