KMS' Potential System different?

It very well may be they changed it. But there's also a chance that there are other factors in this.

1) KMS has a NX trade room where people can sell CS items for mesos (or something around this? Correct me if wrong). We have the MTS, but there's the absurd tax in there that makes selling nearly any small item pointless, making NX harder to come by for a regular player without buying.

You can place CS items on your store permit so there is no NX tax involved, much easier to get around.

KMS has had the potential system for much longer though, it's normal they would have better items than us.