I have been the member of proton-mail since it's beta stage, i think May/June 2014. I know the risks. I may have used it in all this time not more than 10 times....
I cannot think of switching my email account to proton-mail. And when i say my email account, i mean my personal 'cause where i work they already have their own mail server.
I use gmail for my personal mails & they are not that personal that i should be bothered by privacy & encryption issues with Google.
I am concerned about security, but i am not unnecessary paranoid about it.
Ultimate secure privacy is that you have cut all the ties with the real & cyber world. And I definitely don't want that.