The Tascam 564 had the "bounce forward" function, an ingenious and exclusive feature where your 4-track bounce operation would create a new song, leaving the source tracks intact. I, for one, thought this was genious. It enabled you to go back to the source tracks and remix the bounce, if necessary.
The Yamaha MD8 would allow you to take 8 tracks full of data and bounce them down to either 1 or 2 target tracks on the same song, despite if the 2 target tracks already have data on them. This was a destructive bounce operation, but 8x2 bounce was part of the minidisc "magic", an exclusive MD8 feature. On the standard analog system you'd need to have 2 target tracks "empty", and they could not be part of the bounce-down operation, only to receive the bounced data off the other tracks.
The Sony I can't comment on. It looked comparable to the Yamaha MD4.
The Minidisc's 1st recorded track "time" delimiting the times of the entire song and other adjacent tracks was a quirk with minidisc. Earlier HD recorders had the same issue, in the likes of the Fostex FD4 and FD8, IIRC.
My PS5 and DP02CF memory recorders don't care about the length of the 1st track. They'll record any track to any length, despite the others. That's progress for'ya!
