I got these strings for a wonderful Furch Vintage 2 OM. I didn't want the characteristic tone of phosphor bronze with all it's shimmering harmonic content on this particular guitar so I tried a couple of different 80/20 strings for a more "old school" 60s kind of tone. Phosphor bronze strings actually didn't exist until the 70s so they're not really suitable for anyone looking for a 60s kind of vibe. For the tone I wanted with this guitar 80/20 "bronze" seemed like the way to go. Actually, 80/20 strings aren't really bronze at all, even though they are usually referred to as such. 80/20 strings are in fact brass.
I had previously tried the John Pearse 600L phosphor bronze strings on several guitars after reading much praise on various guitar forums. I didn't like them at all, they somehow felt like the guitar was always SHOUTING. They felt stiff and unresponsive unless I played really hard. They were also too bright and edgy for my taste.
After this disappointing experience my expectations weren't high but I wanted to test a couple of different 80/20-strings as I have previously had very little personal experience with this type of strings. The John Pearse 200L set turned out to be my favourite. On a different guitar I might have preferred other strings. You never really know until you try.
80/20 strings are usually referred to as brighter than phosphor bronze but that's really just when they're brand new. 80/20 strings usually mellow out relatively fast (unless you get coated strings of course...). The tone gets far more "organic" and with more focus on the fundamentals than the shimmering wall of overtones you get from phosphor bronze. These John Pearse strings mellowed out faster than most. Whether this is a good thing will of course depend on what kind of tone you're looking for. I'm sure some people will complain and say they go "dead" too fast.
If you like the organic, focused tone of broken in 80/20 strings you will probably love this set from John Pearse. If you want 80/20 strings that retain their new, bright sound for long you should probably look elsewhere. And of course, if you prefer the shimmering overtones of phoshor bronze you shouldn't even consider 80/20 at all.