These blades are the first I've tried in my old style feather professional and I find them to be comfortable and smooth but are the sharpest blades I've come across including straight and all the DE offerings.
Longevity of these are excellent making them a great buy.
These blades are what you would expect from any standard straight razors. They are very sharp and give a good shave, the only reason I give them four stars is because the super pro will give you a much closer shave. For some, these blades will be more than enough however.