To the OP:

There are two things that your 5D Mark II lacks that I find I need in a light meter:

1) a built in incident metering mode; and
2) a flash meter function - particularly one that reads in incident mode.

You can kludge up a pseudo incident mode with a grey card, but it is far from convenient in comparison.

I would think, given the wide variety of cameras you have and use, that it would be advantageous to you to standardize on a single meter, and then calibrate your various cameras and lenses to that meter.

The 5D Mark II is a system, that may involve different lenses, metering patterns that may vary with different modes and other variables.

How well does it serve you if you have to account for those variables?