Take your pick, trowe,

And read the attached link. Ultimately, it's up to your "LF" to decide what she wants. In addition, please remember that some women can truly orgasm from vigorous nipple play, so this is an area where you will only score points if you grant her wishes.

As for "safety and effectiveness" - again, up to the clampee. It's not rocket science, so things are fairly simple in terms of attachment and removal.

Don't overcomplicate, just clamp it,
The Love Goddess

It's obvious you've never talked to a nursing mother

"LF argues that her nipples are tough and can take a lot of abuse.  Is she correct?"

The thickness of the line between pleasure and pain varies from person to person. And of course, with each person, the place on their body, and the levels of adrenalin and hormones running through their body.

I experienced my ex-wife's nipples texture and sensitivity changing dramatically every time she began nursing. Her nipples would get to the place where they could take a lot of punishment, but once the teeth came in, the kid was on his or her own.

If some descriptions I've read are accurate, some guys go for hard squeezing and general rough play around the sack.

I, on the other hand, can only take very light play.

Each gal is different and I try to be accomodating, but I have to draw the line at hard biting.