Hi!
Just to let you know where my problem is:
It is the resistance between RX and 5V.
It should be measured as about 1k to connect either MIDI or USB.
So I can't for now have a standalone solution where it is possible to connect the FTDI from time to time because the resistance is then too low or too high without the FTDI.
I can put a switch to enable a parallel resistor to the 3,3k one : enabled would be MIDI, disabled would be FTDI.
Or perhaps a transistor?
Or a FTDI in my enclosure... I made eveything to not have the need of it, but... And it would allow me also to have MIDI over Serial/USB connectivity.
So, for now I don't really know. I could try a transistor, but would it allow 9600 or 11250bps? I'm not sure with a 2N2222? (Their frequency is 250MHz or 300MHz)
Another thing: check out Ruin&Wesen library, could help some!

http://ruinwesen.com/blog?id=582