For several years my perfect pairings have been a Red Pack (UK) Personna in my SuperSpeed (winter razor) and a Merkur blade in my 34G (summer razor). Last month I tried an Astra in my SS and was surprised to find it sharper and smoother than my favorite Personna. I have now switched blades, something I never expected to do. Next month I take out my summer razor and I'm hoping I get the same results with the Astra in the 34G.