I recently found some interesting and simple HD wallet design here: https://bitcointalk.org/index.php?topic=5321992.0
Could anyone see any flaws in such design or is it safe enough to implement it and use in practice?
If I understand it correctly, it is just pure ECDSA and SHA-256, nothing else:

masterPublicKey = masterPrivateKey * G
masterChildPublicKey = masterPublicKey + ( SHA-256( masterPublicKey || nonce ) mod n ) * G
masterChildPrivateKey = masterPrivateKey + ( SHA-256( masterPublicKey || nonce ) mod n )

Also, it has some nice properties, like all keys starting with 02 prefix and allows potentially unlimited custom derivation path by using 256-bit nonce.