Because it's my understanding that the "String Theory" forum/ thread remains under Mod discussion, I'm posting here:
I just noticed that the only concert/ soprano Martin strings sold by Musicians Friend are M600. Though I had a problem with a prematurely fraying A string last year that prompted me to switch to Fremont Blacklines, after re-listening to the following September 2022 cover of Skynyrd's "The Ballad of Curtis Loew", I realized: (A) I was still using M600s at the time; (B) The strings sounded pretty freaking great, particularly on the final 'chime' note to close the outro, and (C) I was standing at least 12 inches nearer the smartphone than I usually do, which may explain a certain portion of sound clarity and any perceived overtones (not sure that's even the correct term).
Anyway, next time I need strings, I'm now strongly considering changing only the high-G, C and E to Martin M-600 and leaving the D'Addario A in place. Along the same lines as the OP's original question, is anyone aware of any downsides to doing that?