Both Keepkey and Nano S wallets are suitable for safe storage of SMSF investments as well as personal investments.
If your wondering which wallet is best for you, there is a good review/comparison on Youtube here : https://youtu.be/1HjgiJ9B9i4 . Keepkey is a new hardware wallet addition to our range. KeepKey is a hardware wallet that secures bitcoin, bitcoin cash, ethereum, litecoin, dogecoin, dash, and namecoin. Over and above storage of these coins, it offers a different user experience both on the device and when shopping online to the Ledger Nano S - see video above. We would rate both wallets (Keepkey / Nano S) equally safe for storage of your coins/tokens.