Who?

[Overread]

For a regular 100mm macro you should be ok if it is a really good ballhead. However some do suffer creep (this is can either be when you release your hands from the setup after locking the ball in place and/or when you leave the setup for a few moments - the ball can creep down with heavier or less centrally balanced setups or creative angles).
This is mostly a pain for framing with and - whilst I fully admit it is a lower grade ballhead - it was one thing that pushed me from the 322RC2 head toward the geared head for macro work (regular lens use does not show the creep factor)

 

[davebmck]

Yea, I had the 322RC2 head before I got the RRS ball head. It was a nice ball head, but just wasn't adequate for my 500mm. The RRS BH-55 is rock solid when locked up.