Okay, first & foremost, I am so sorry for your loss. We too have lost a couple of feline buddies. Kids cried. Terrible. We had to learn the hard way. As now are you. Here's the thing, they're cats. A cute 15 to 20 pound, domesticated, curious, bell wearing, unarmed creature. Once you let them out, they're on their own. Except for the dogs, the raccoons, and the skunks. And let's not forget Princess Cindy on the phone in her black Jetta. "Oh my god! I thought I heard a thump!". Oh they might last for a few years, sure. But your current score is Spokane 7 - Mittens 0. Keep them inside!