I think Myetherwallet is a good storage for huge amount of coins for as long as the private key is safe or even if you use your ledger to open the site. I did store mines but I just withdrew them because I need the money for emergency, but I had kept it there for a year or so.
I think the same with you
as long as we can still keep the private key we can still save in myeterwallet but I suggest do not use a one wallet only because to better maintain our assets when hacked we still have assets in other wallets