I haven't.....
I have not taken the time to learn it's in's and out's, but I worry about it, that it's becoming more and more embraced globally. I think there's an inherent danger here in the fact that if it becomes so popular, it's perpetuated in to a "world currency." And, I feel that when that happens, those in power are waiting in the wings to pounce on it with their experienced retinue of manipulators who will then control the funds of ordinary working people globally. Be careful what you wish for kids.
I think it a dangerous dalliance along a precipice.