I've have this 20lb orange tom named Garfield I got from the humane society for about a year now. Great cat, and I've been letting him out on my back deck because the 4foot railing seemed more than enough to keep the big guy in bounds. He's never tried to jump the rail in the past, and isn't a keen jumper in general because of his size. He's not fat, just huge.
For the past several months we've had a black and white alley cat wander the neighborhood causing all kinds of raucus. He yowls constantly, sits in windows and drives indoor cats (and dogs) nuts, walks in mud muddles and the finds freshly washed cars to sit on, poops in the next door lady's garden, etc. Owner refuses to keep him inside, and if it wasn't for the fact I like animals I'd end the problem with my 9mil.
I let Garfield out on the deck the other night, and went to work on my computer. Heard a loud cat scream about 10 minutes later, and went out on the deck to find Garfield not there. I quickely ran around looking for him, only to find him sitting in the neighboors back yard licking his paws and seeing the alley cat from hell beating a hasty retreat. Seems Garfield jumped the fence just to kick some ***, and calmly and proudly walked back to my house with me saying 'good kitty' behind him.