feather blades

Feather blades are my favourite blade.  The vendors insist that the yellow and black packaging are identical and the only difference is 5 or 10 blades.  I agree, or at least I can't tell the difference.  I'll use a feather for a full week of 6 shaves.  I've gone longer but why should I?  I find that most blades, including the Feather are razor specific for me.  When I started out wet shaving with a EJ DE89 I did not like the Feather but as I've acquired more razors I've found the blade to work better for me in some razors and not in others.  It works very well in the Rockwell 6s, most of the Ikons, the Karve CB and the RR Lupos.  

Good prep and a good soap/cream are more important than the blade nowadays as most coated stainless DE blades shave very similar if the aforementioned is adhered to. I would wager money that if shaved by a professional barber who had done good prep and used a good soap/cream not one man jack on this forum, or any forum for that matter, could tell any measurable difference in the DE blade said barber selected.