larryi,
I absolutely agree with your observation on Sheffield recordings. The thing I like most about them is no "engineering" or audio manipulation of what was played. It's a direct path from a single point stereo mic to the cutting lathe. As often as possible (which isn't often) I like to hear what was played, rather than some engineer's impression of what he thinks it should sound like.
I like those you added, particularly Kate & Anna - I have a couple copies.
I like several of those (haven't heard the others) on Dorkwad's list, especially Eva Cassidy's "Live at Blues Alley".
Only a couple others to mention at this time because there are too many:
Stanley Clarke's "Journey to Love" (with Steve "In Gadd we trust" on drums). A favorite of mine for almost 50 years.
Radka Toneff - "My Funny Valentine" ..from the album Fairytales (Odin Records1982). Other than a Miles Davis instrumental, (imnsho) you haven't heard MFV until you've heard this one.
and last, but not least - The Dallas Symphony Orchestra (Donald Johanos) - Rachmaninoff's Symphonic Dances Op 45 - VOCALISE OP 34