Thank you for your response. Here my comments to that:

1) Passphrase and SeedXOR have similar complexity. I understand the point, that more complex solutions increase the risk of loss due complexity. Anyhow, that has nothing do to with my question. 

2) Why is a SeedXOR easier to restore? Please explain. 
In my opinion Passphrase is easier to restore and supported by most wallets. 
Furthermore the seed phrase of a passphrase secured wallet has the same deceive feature as the seed of a SeedXOR. You can load both with „ready to lose funds“ to deceive an attacker. The attacker doesn’t know that a bigger wallets exists in both cases. 

3) what is the difference in the attacker having the seed phrase of a 256 bit passphrase wallet or a seed phrase of a SeedXOR wallet. Please explain.