I said it was the older version of the rod. Much stiffer than it's successor which my friend has. I fish plenty of 6 & 7wts and comparatively to my 7s it fishes like a 7/8 both in required line weight and the size of fish needed to make it any fun to fish. I have both a Beulah Platinum & Echo Full Spey in a 6 and they're right around the 420 mark for scandi, the Beulah prefers something a little lighter depending on what I am throwing.

I don’t go by the large grain windows manufacturers are stamping on rods nowadays, a 6 should be in the 400 Scandi range and 450 skagit zone! 510-540 is a 7wt.
I agree, they should, however this is not.