I regularly hit the top end of the leaderboard using my favorite character the Fire Chomper but I do agree with some of the points. The main thing I would like to see is a decrease in the digestion time, which can be a little too long even with the upogrades. It makes it impossible to kill in a group situation but I guess maybe that's the way the chomper is designed to be played, not to get involved in groups but pick off individuals.
However if you do eat somebody and there is another zombie anywhere nearby you know you face certain death, it would be nice to have some kind of escape plan.