I'm probably more of a supporter of old-school methods, because in my case I trust my private keys only to my paper notebook. I don't use any other media anymore, and I'm very suspicious of any electronic media that can help save passwords or any other sensitive information like private keys. For me, my notebook, locked in a drawer, is a fairly reliable tool.
If you think it is the safest place then keep it there. Because I think the one who knows the safest place is ourselves. Maybe other people's input or experience can be a reference for us to save something important, in this case the wallet's private key. But then again the one who knows the safest place is ourselves. Because if we follow what other people do sometimes we forget where to save it because we are not used to it.