I just re-listened to those baritone/piano and guitar tracks recorded on the Coles 4040 referenced in Jim G's post two up from here and must say on fresh listening that they both sound smooth and natural up to 8kHz, but on re-assessment they sound distinctly rolled-off in the higher frequencies.
If the guitar were live, I would expect to hear more pick sound than I am hearing, and the equivalent amount of top is missing on the baritone/piano recording. What is there is beautiful, though.
So, I withdraw my unqualified approval of these.
Even more off-topic, I am just in the process of re-mixing for re-release three of my older recordings most dear to my heart - all recorded with ribbons in un-corrupted Blumlein, one with the Speiden SF12 and two with the Royer SF12 which was based on the Speiden (which was, in turn, based on the B&O from the 50's. The two Royer ones are solo piano (Paul Cantelon) and the Speiden one is the 1994 recording of the 95 piece orchestra in Kiev. This time, they should have wider availability, and when they are actually released I will let the AC community know.