Girdles are great. I've welded new stud bosses on lots of BBC aluminum heads that have gotten wallowed out or the whole chunk of casting containing the boss broken totally out due to stud flexing.
All you guys who say they are unnecessary may need to review the sage words of Patches O'Houlihan from Dodgeball..Patches O'Houlihan : Necessary? Is it necessary for me to drink my own urine? No, but I do it anyway because it's sterile and I like the taste.

It's arguable whether girdles are necessary, but if you're on the fence I say go for it.

I had a boss break of last year on a head that had run shaft rockers from day one.

Have you ever run into that?

What shaft rockers. What lift and duration cam?

Jesel

Talking to the guys at JOMAR, there are small differences in valve angle and therefore stud placement between the different head manufacturers. You may have had a stud girdle that had a different alignment than your studs which caused the break.

No stud girdles, shaft rockers.