I should receive my new stone today. I will primarily use it for maintaining my straight razors.

I own a 6" x 2" DMT Course/x-coarse diasharp stone.

I believe the Naniwa is 8.25" x 2.75".

IMO I think my DMT should work well flattening the Naniwa since the Naniwa is just a little bigger.

The other options for me would be to buy wet/dry sandpaper. If I went this route, what grit should I use?

Which method should I use?