Maybe on an i-Pac 2 but check the first few posts of this thread. I have an original i-Pac, which I bought in 2001. When I use it in PS/2 mode, everything works great and I can pull out the move without much problem, and I'm basically limited by the physical strain, not the the encoder. However, in USB mode, there is simply no way to pull it off, no matter how fast I shake my arm.
It's fine, though, I've decided to continue to use it in PS/2 mode and just get an adapter for my PS/2 tracbkall and spinner combo.