When I was in my 2nd year of college, 1967-68, my roommate had a Gibson B-25, which he never played and which he very much wanted me to play. And I had no 6-string guitar at the time, only my Harmony 1270 12-string, so I got a fair amount of playing time on the B-25. I thought it was a very nice guitar, but that was pretty early in my guitar journey, so that I can't say that I had a great perspective on how that guitar stacked up against small bodied Martin guitars.
I had no problem with the narrow nut width and never spent any time thinking about this issue. I'm sure the guitar had old strings -- they all seemed to have old strings in those days, including my guitar.
I have a soft spot in my heart for the B-25, but it did seem very much like a student model when I think back on it.
It sure was pretty -- the one I played had a very lovely sunburst finish.
- Glenn