Okay, I tried P2Checksum and didn't really care for it.
The delay during opening (splash?) screen killed it for me. I saw no way to turn that off. The readme says "P2CheckSum instantly analyses the file". Well, it wasn't so instant with that opening delay.
Also, what does the little "P" do in the lower left. It looks like it is selectable, it highlights. Didn't look like it did anything.