I have tried the Supers, Polsilvers, Feathers, and Personna meds, which are all supposed to be in the same bracket.

I tried them in three different razors for three shaves.

37c - feathers (smooth for all three and sharp ATG)
Super I (smooth for all tugged ATG shave 3)
Polsilvers (smooth all tugged ATG all 3 shaves)
Personna Med (nicks shave 1 smooth 2,3 ATG tugged 3)

EJ 89 Barley - Feather (nicks 2 shaves ATG sharp all three)
Super I
Polsilvers - (tugged all three almost gave up)
Personna Med (smooth all 3 and started tugging ATG on shave 3)

'57 SS Red Tip - same results pretty much as the EJ except Supers were smooth and performed like Meds

I concluded and this is just my findings that the feathers performed best for me and I keep a wine cork in shave den to lap them if using in EJ or SS.