It does pay to report the all-in abusers. I've done it in the past and received the usual "Yes it was suspicious, but... blah blah" However I persevered and finally, today - SUCCESS!

"Thank you for taking the time to report a potentially suspect usage of the
*disconnect protect* feature.

We have thoroughly investigated *xxxxxx* account history with a particular
focus on their previous usage of this feature.

We have found that the hand you reported to us was indeed suspicious and as the
investigation has revealed further suspicious disconnects in the past, we have
proceeded to block the protection feature for this player. In future, should
they disconnect their hand will be folded. The player concerned has been sent an
email explaining the reason for our actions.

If you need any further clarification, please do not hesitate to contact us.

Contact us anytime, we are available around the clock to assist you with your
account related questions and suggestions.

Sincerely,

xxxxx
Investigations Team"

This was from Party Poker, by the way. Just write down the user name and the hand number whenever it happens and send an email after the session is over... it's well worth the 30 seconds it takes.