I've used DR Extras for a number of years as gigging in a club/function band around 100 times a year I found I was going through lots of strings.
With these coated strings I found that I only had to change about 3 times a year, and often that would be more for cosmetic reasons than tone.
When these strings go on, they don't have the same brightness you'd get from a set of brand new steel roundwounds, they have a crunchy kind of tone similar to a set of nickel roundwounds which have maybe done a gig or two.
They stay sounding that way for ages though. I've had sets which have done 30 gigs and you would never know from the tone they weren't new.
The colour coating does flake a little over time, but not so much that affects the sound, only the appearance. This is more of an issue if you use a pick.
I have one gripe with these which is that DR have recently changed the coating to something called Dragon Skin or K3 and while it may be longer lasting, I find it quite uncomfortable when doing a lot of slides as the friction causes a burning sensation too easily.
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