(IMO), where this proposal really excels, is mutlisig.  And if you check my commits, it actually originally was for multisig only, and I extended it for multisig and single sig wallets. 

ghost43 and Jochen Hoenicke brought up important issues with this proposed BIP re: single sig wallets, so I will be reverting this back for multisig derivations.  I believe that should cover all concerns.

Please view the updated BIP here: https://github.com/Rspigler/bips-1/blob/Sane_Mulitisg_deriv/Modern%20Hierarchy%20for%20Deterministic%20Multisignature%20Wallets.mediawiki

And the updated PR here:  https://github.com/Rspigler/bips-1/pull/1