I've tried several morse keyboards for android, but all of them seem to be more fun than useful. if only I could get a cross between the hackers keyboard and morse, I could stop finger fucking these tiny screens and actually type what I want
The world record in sending letters (random 5 letter groups) is 283 for one minute: http://www.hst2017.org/en/records
This is with a special key that's made for high speed telegraphy. Anything on a mobile device would most likely be a lot slower.
There are some sample sounds of similar speeds, which you may find interesting.