Since you brought up the scientist and Uni, I would like to add that you can really see what an unfair advantage the scientist has with his take downs. Both these characters can warp then kill, but only one can avoid certain death afterwards. After Uni warps then chomps, there is that death-sentence cool down period. So you trade you life for one kill. The scientist, can kill several others, then warp to safety, heal up, and get right back in the fight, without having to even worry about respawning, and crossing the map again.
The scientist is one of the deadliest characters there is, and it would be nice to either give Uni the same ability to instantly warp away after a kill, or else reduce the scientist to only 1 warp with a decent cool down period, so if he comes in to kill, chances are he ain't leaving alive.