I have been on the geep now for a year. I convinced myself I needed something faster/sleeker/more fashionable but to be honest, if you spend £1500 on a GPZ you will get a bike that will keep up with the majority of 600/650s on the road, costs pennies to run, and will last until it falls apart in many years time. Compare that to your more modern sports bike which will comprehensively outclass it, but will melt the first time you get it wet!
The bike is 120mph fast, but you can still redline it around town if that's your thing without getting nicked. Dirt cheap insurance. 70MPG if you take it steady.
5-7000 rpm will see you 200 miles to a tank and will still get you to 85mph fairly briskly...give it a handful and the bike will reach 100mph in a few seconds.
Watch your tyre tread and head bearings for tightness/wear (not too serious) and the handling will stay true right up to the top speed.
To be honest, this bike is frowned upon by the power-ranger-suit brigade, but if you actually ride all year round, not just pose at the weekend, you cannot go wrong. Plus, I actually like the retro styling...there are few bikes on the market that have a 25 year production run and are still being sold now pretty much unchanged...there must be something right there!