Cutting LEGO (a.k.a. Yes, it's ok to mod a brick sometimes...)

I need to cut a LEGO plate into two pieces. Specifically a Round 4 x 4 plate with Hole
4x4 (Part number 60474). I'd like to bisect it into two 2x4 segments, but I'm not sure of the best way to do it.
Should I use a sharp knife, a saw, or a burning hot wire to melt right through it?
I'd appreciate anyone's input on this.