According to a document I downloaded from the RMG website years ago, when they were the manufacturers of what are now the RTM tapes, back coating on open reel audio recording equipment:
• Allows generally good running properties
• Allows mode flat and smooth winding packs during fast winding
• Is antistatic (if black) and avoids click effects during decharging
• White backcoating allows manual marking during handling
According to my own experience, backcoating is problematic on machines with felt pads pressing the tape on the heads (eg. the Uher 4000) and most machines with stationary guides on the back side (notable exception: the Nagras, but these have extra-smooth guides unlike the consumer decks with plastic guides). In this case friction on the back is increased, and moreover aging backcoating (if black) tends to leave the tape and get stuck on the pads / guides. Uher recommended BASF DP26, which was not backcoated. I don't think non-backcoated new tape still exists, AFAIK RMG's VM 950 voice logging tape was the last one, RMG recommended it for operation on the Uher.
• Allows generally good running properties
• Allows mode flat and smooth winding packs during fast winding
• Is antistatic (if black) and avoids click effects during decharging
• White backcoating allows manual marking during handling
According to my own experience, backcoating is problematic on machines with felt pads pressing the tape on the heads (eg. the Uher 4000) and most machines with stationary guides on the back side (notable exception: the Nagras, but these have extra-smooth guides unlike the consumer decks with plastic guides). In this case friction on the back is increased, and moreover aging backcoating (if black) tends to leave the tape and get stuck on the pads / guides. Uher recommended BASF DP26, which was not backcoated. I don't think non-backcoated new tape still exists, AFAIK RMG's VM 950 voice logging tape was the last one, RMG recommended it for operation on the Uher.
The Monitor series did not have a pad. They still had plastic stationary guides though, so they might still have problems with aging backcoating, although probably not as bad. Back when I had one, I remember using it with PEM 468 (a tape with black backcoating) and not having problems, but that tape was fresh stock back then. I don't know how it would cope with older 468.