Just thought of a good idea (i think), but what about a script that if you knife someone (unless you are on a knife level, obviously) you don't steal a level, but instead, the players swap levels. So if you are in 1st place, it would not be a good idea to knife someone, but if you are falling way behind, you can catch up quick and even take the lead by knifing someone. Although, you might need an obvious way for people to know whether or not the person they are going to knife is of a higher level or not. And if they are on the same level, maybe just do normal level steal.
Satoon