I usually stick to one distro as well, once I'm settled. I did switch from Ubuntu to Debian when I got a new computer, but that's about it.

But I do understand distro-hopping - it's a bit like getting a new camping stove is for me: I have a perfectly good stove already, but I purchase or build a new stove every now and then in search for that elusive perfection, or just to try out something new. But unlike the stove, which can be seen as an extension of my identity as an admittedly urbanized outdoorsman, the distro is just a tool like a hammer or a screwdriver - no need to try something new when the old one works perfectly for what I'm using it for.