As a keeper of both, I've never had any *real* problems. The few escapes
we've had in the past were to a very young Grimmy being overenthusiastic
with the Sams Tube setup, but he never hurt them. In fact, he usually
tracked them for me. "Hmmm. The cat is staring intently under the stove,
and the gerbils are loose. Hmmm." But it can be done. I even built our
cages so he has a perch (with his own blanket) to snooze on. It's his
favorite spot in the house. Now he sees them as more entertainment than
anything else. He horned his way into SEVERAL of the shots on my site,
check it out.
http://www.geocities.com/cjkeil/