I have the Nisenson book but was not familiar with the other one; thank you!
Regarding tape speed, I believe 15 or 30 ips would have been fairly standard at the time.
By far the best K.O.B. I've heard is from HDTracks. This version sampled the tape at an extremely high frequency using a special head- not because a '50's pre-Dolby analog tape needs that kind of bandwidth for audio playback, but because the high bandwidth allows the producer to 'see' the bias signal on the tape. Think about this: When the bias signal was generated, it was an electronic steady-state signal. When they play back the tape, there are variations in the frequency of this signal which correspond to wow and/or flutter on the master tape. By performing digital processing on the high sample rate source, they can literally use this signal to tune out almost all wow or flutter in the original master tape
. The result is quite an ear-opener- much more clear and- surprisingly- noticeably lower hiss. The process is called the Plangent Process, and here is an explanation along with some before-and-after documentation
. I don't know if that SACD is done from the Plangent remaster, but if it is, your ears are in for even more of a treat.
'Kind of Blue' is a masterpiece and rewards listening on anything, at any time.