They are old, yes. Stronger then a normal account, no
The reason pre 07 accounts are valuable is you can add a merchant account without having to supply records. However, other then that the account is pretty much the same as anything else. You can get limited, shut down, etc.
To be honest, you are really much better off just making up your own stealth accounts. You really dont want to harm your nice friendship now do you. Naturally, it would be unintentional, but it can blow up in your face.
Dont let the age of the account give you false confidence. It really is just the same as any other..... | 
