Personally I'd never create a clay golem, simply because of that berserk chance. If you take the golem into combat, you will eventually roll low on your d%, and lose the golem forever.
If you look at the probability, the cumulative odds really suck. The chance of your golem going berserk in round 1 of a given combat is only 1%. But if the combat goes on for even 5 rounds, you have a 14% chance of failing on at least one of those rolls.
Assume every combat is just 5 rounds long, and you fight just twice per day. That gives you a 45% chance of losing control within two days, and an 89% chance within a week.
1% per round may not sound like much, but unless your dice are loaded, you cannot avoid it for long.