Indeed a nice write up.
I have bought some leonardo 's and in contrast to Si I had some bad experiences.
The first thing that completely baffled me was the double use of the USB. The USB port uses 2 com ports. one to upload and one to use for the serial monitor. Both ports are not active at the same time. Which means that when you plug in the board first the Upload com port is activated (pling) then it disappears (plong) then the serial monitor com port is activated (pling). On my system that means lost of sound (pling plong)
When I rest the leonardo it goes (plong;pling;plong;pling)
I was surprised not to read anything about this behavior in the article.
Maybe it is a windows thing? (I'm mostly using Windows)
Then I got problems with 64bit RXTX dll. ( I admit I'm not using the Arduino IDE)
That is when I switched back to the old boards. Maybe I should take a new look and stick to 32 bit tools.