Grace Level ll

has anyone had any experience with these cartridges? Seem to be compatible with the earlier F8 cartridges, but with better cantilvers and stylus.
Can you provide more information? I've never heard of "Grace Level II". I own and enjoy a Grace Ruby. Thanks.
The cartridge line came out in the mid 80's. I believe it came out at the same time as the F14. The level 11 was based upon the F8 and the F14 was based upon the F9. They had upgraded parts, styluses etc. The one that I am looking at has a Boron Cantelever and a Microridge stylus. I am not sure if they had still offered the F8 or the F9 at the same time. I believe the F8 and F9 were from the 60's and 70's. The vinyl engine's cartridge base lists these cartridges and some of their specs, but I have not been able to find out a lot more about these. I believe most of these were offered in Japan and then Sumiko brought a few in. So they are rare cartridges. The seller is asking a comparable price to the Ruby. He considers the Level ll an upgrade from the F9. I am trying to see if anyone has heard one of these. I found 2 that sold in the past year, but have not got info from them.
Given the wonderfulness of my Ruby, I would be curious to listen to an F14. The nomenclature is still a bit confusing to me. There is "Level II" and within Level II there are F11 and F14? Is that correct? I've never heard of these cartridges maybe because I have not paid much attention to those very late Grace products. However, I do think the Ruby was made well into the 80s, at least. Correct me if I am wrong.