The first port uses the hardware serial at baud rate 115200 (or something else), but not the baud required by the MIDI standard. For now this is mainly a baud rate converter.
Regarding why I read regardless of whether there is anything to read it is for two reasons.
Firstly it is one way to get something back. Basically it is an indication that I get a proper message back through the HW serial. It is a simple diagnosis that helped me see that there was nothing to read.
Secondly there should be something to read. Perhaps with some delay added in between, but there never is. Not even after a few iterations. The serial port called MIDI is directly wired to itself, TX<->RX, shouldn't that allow reception of the sent message on the same port?
These two lines are not in the original sketch, but were added when I saw that I got no data on the second Arduino. At that time i removed the second Arduino and tried to get a message through software serial by short-cutting the lines on only one device. I have the same problem on both Nano and Uno, so I am sure that I am doing something wrong... I have very little experience in this so if you have suggestions I will be happy to hear them.