I've tried several kinds and the one sold by the Urine-Off people is definitely superior. It has something to do with the UV light spectrum it emits. Not all blacklights are equal. The Urine-Off's light simply is better at making urine flouresce.
Sorry to hear about Butch. That's a real problem. At least where you live there's public acceptance for outdoor cats. That's been the only solution I've been able to come up with, and here it's illegal for Rocket to be out, but he's out there anyway. So far nobody's turned him in, but I think the neighbors are getting a little tired of seeing an orange cat on their property.