Awesome coin and great writeup! Thanks for giving us a window into the early history of Florentine medieval numismatics!
I’m going to bump this thread with a little update. After about 4 years of searching, I was finally able to secure an example of the “prototype” variety! It was unattributed in the auction, so it sold for 1/3 my max. This is the fifth example to come to market in the past 20 years, and it is the finest of those five. Well worth the wait!
Wonderful coin ! From all the other examples you posted for comparisons, I notice that the rev. legend is very often blundered, and this from the very beginning. The "prototype" has B.+.IONANNES. There are even some others with +.S.IOHANNE.B. ! which means nothing...
Beautifull coin! Medieval coins are underated/ most have great designs, like your's. Congrats on your addition. John