Choice is just as wide ranging, every tyre you would have considered for your Kwak is available in those sizes too.
Handling wise, you won't notice the narrower tyre if that's your question. Most people use sport-touring tyres, I do, but I'm tempted to try something more racey this summer.
I'd say have a go on one somewhere, at a dealership. The v-twin isn't to everyone's taste, you'll find the engine braking intense after your Z, and not everyone gets on with the S riding position either. The brakes are cheap, but as long as they're well serviced are ample (a K4 will be due brake hose replacement btw). It's better than the sum of its budget parts though, and with a few fairly cheap add ons can be made a fair bit better still.
I've ridden plenty of faster bikes, and some much faster bikes. I occasionally feel like a change, but the SV just seems right for me, at least for now. More than enough to embarrass bikes with twice the power on the B roads too. "That a thou'?" "Nahh".