If Derby Extras are cutting you there is an issue with your razor or technique. I use these blades, Astra SPs and Dorco Stainless/Prime with great results.Smooth and mild... like a camel. Maybe not so much.
I have a RR Mission that's been giving me trouble. Before I go and get a whole new razor, though, I thought I might look into some milder blades.
What I've tried so far:
Gillette Silver Blue (best performer yet, though still harsh and one of the more expensive blades)
Astra SP (a great blade on the 4th-5th shave)
Derby Extra (green, cuts me)
Bic (cuts me)
Treet (doesn't cut the hair)
Rapira (cuts me)
I have a sample pack ready to order from tryablade. My selections include:
Persona Lab Blues
All manner of Sharks
Dorco, platinum and stainless
Kais (just because I'm curious about the super blade)
Am I barking up a reasonable tree? Am I missing anything? There are a lot more blades on their menu, I just don't know much about them (other than the facts that persona LBs come well recommended, and I had good shaves with one of the sharks in my Lord L6, though I have forgotten which shark...)
Get yourself a King C. Gillette razor and see how that works with your blades. I've found it to be an excellent mild razor that, with the right technique, can deliver BBS shaves with minimal chances of nicks. Another B&Ber, who was having serious problems the weepers purchased on of these and it delivered great shaves.