my new and improved 4-point grading scale

[T206Collector]

I guess I really am approaching this from an old school angle. If you stop to think about it, the grading companies did that, too. They only use the known parlance, but add qualifiers like "near" to mint -- kind of like adding an 11 to the volume knob.

[Doug]

I'd put NM back in and go with this 5 point scale:

5. Mint
4. NM
3. EX
2. VG
1. Poor/Fair

The gap in condition between EX and Mint is too big to leave NM out IMO, otherwise I think your scale is on point.

[Mrc32]

I find it interesting that your Trader Speaks grade chart does not mention centering at all.