The countryish/Chuck Berry guitar licks at the end of the song - KR or MT? Sounds more like KR but I've never heard him end the song like that in concert.

the ending licks have always sounded like both to me. Keith playing double string licks and Mick playing single string runs. Just my opinion.

it ends in a Gchord and Cchord jam of sorts, high up the neck the end chord is a C

Those licks are played in standard tuning, but the very last one...on the G chord (before the final end in C) comes in open g tuning; so it's a change of 2 guitars - at least that's how I have to play it

ON the studio version it's Keith playing the Berry-licks in standard tuning. MT is not very audible on Brown Sugar.

Interesting. What about the 4 note riff at the start of the chorus (before Brown Sugar, how come you taste so good?) It's definitely in G tuning. I just assumed it was Mick Taylor because I couldn't figure out what else he could have played in the song but maybe Keith did a lot of overdubs on that song. KR definitely plays the main guitar and the acoustics. Maybe MT's involvement was mainly the slide guitar on the early version that was later (and wisely) erased.

I think I remember reading that Mick Taylor played a guitar in open G on "Brown Sugar". That may or may not be true. Can't remember the source exactly.