i'd be safe to say the casualties with non leathal rounds would most likely be more severe.

the idea is you shoot someone, and then they know you're serious. non leathal rounds do sometimes kill-- the problem is that people will get the brihgt idea that they can jsut run right thru get hit 5 times and be scott free, do that 10,000 times and thats lets say 50 dead vs like 5 or 6 with leathal rounds that are more effective at keeping them back anyways.