what surface area risk ?  my multisig is secured with 2 hardware wallets plus a key kept by casaa. ETH available doesn't change anything as far as I can tell. Having my 2 hardware wallets necessary to sign any transaction in different locations is what provides the security of the setup. 

 would you rather have a company concentrate on only bitcoin or many other ones at the same time? you don't see the unnecessary risk in that hint ledger etc