Most pirates on iOS are simply using one of the free tool and don't go far beyond that. I have implemented a technique for detecting pirated app and used it now in many apps: since then the piracy rate went down to zero which convinced that most pirates on iOS are simply using a tool and don't know what to do if the app they try to crack fail.
I am sure that a true pirate will find way to bypass my security check but so far after more that a year of implementing my solution in all my released app I didn't find anymore pirated copy.
If anyone is interested to learn what can be done, send me an email.
Are you checking that the Mach-O binary is encrypted? I'm not aware of that being worked around by any of the automated tools (and it an approach that is widely discussed).