Sam, I don't know specifically, but what my experience has shown is that Feathers get dull pretty quick and generally do not last as long as the others you have named. Kai blades in my experience last on average about as long as the Personna hospital use, Polsilver, and Super Iridium blades. I think Kai blades cost more. A few years ago I tested all of those four brands and the results were a range of between 5 and 8 very good shaves before the edge began to deteriorate noticeably. The extremes of 5 and 8 shaves were rare, and most blades (other than Feather) averaged 6 to 7 good shaves before noticeable deterioration. A brief internet search based on price and availability reveals varying results. You should get just a few of each so you can discover which ones work best in your razor of choice. Kind of like buying a pair of shoes, the bottom line for fit and performance is subjective, and the only opinion that counts is that of the owner. You might decide that you want to stick with more than one brand of blades in the long run. One other point, I'd highly recommend choosing your new razor before you start looking at blades. You might decide on an SE or a DE razor, or both. Good luck!Sam wrote:How are Kai compared to feather or personna med prep? Or polsilver or Iridium silver?
PS: I highly recommend http://www.tryablade.com/