Know this is an old post.
I've got some Joest SG/SG2 Pads from a few years ago. Joest sent me some samples.
Saw the CTD Pads this past week. Needed to borrow a 3000 pad, seemed to do the trick.
Going to put a couple in the bag to compare to CTD.
Did you ever figure anything out in regards to this question?
Edit-
SG2 Pad Grits: 1600, 1800, 2000, 2500 (sent to me)