I've brewed several over 10% and with positive results. The only issue i have ever had with these types of big beers is the first couple times i bulk aged them for several months and i ended up with very low carbonation because i had almost no yeast left in suspension to carbonate. I was still fairly new back then so i didn't understand enough about carbonation and yeast in order to properly bulk age.
I believe Homer Simpson said it best "Alcohol, the cause of and solution to all of life's problems"
i helped my bro make his first beer a long time ago and we screwed up and it was around 16% alcohol. It was disgusting to drink, picture drink straight rubbing alcohol. I think the beer was supposed to be a lager at ale temp too.
Been brewing since 2007 and my knowledge is ever growing.