"We have two cats, one of whom has chronic cystitis. After nearly two years and two vets, we finally have her problem under control with some great prescription wet food and medication.
But through the whole process, she got a little too accustomed to not urinating where she should ... and our other cat would sometimes follow suit.
Once we got the medical issue taken care of, we tackled the behavioral problem in part by using the Feliway plug-ins. We have four going now (we have a two-story house, and the cats run the place, of course). And we've had very, very minimal urination issues since. I can't say for sure it's the Feliway, but there was definitely a noticeable difference since we started using it.
And I say "If it ain't broke, don't fix it!"
It's definitely worth a try for those dealing with behavioral urination problems. But make sure you have any medical issues taken care of first, or this won't do you much good."