Well the point of more motors is lost when the amount of force is determined by the friction x the weight of the bot. More motors just makes more of your precious weight taken by stuff that does not damage the other guy.

I suppose you would get better acceleration and higher possible top speed but keeping control of the things seems to be more of an issue than speed.

Again the challenge of maintaining force whilst the bugger lifts you you and thus gets all of his drive down and you slide backwards is significant.