I have a 2003 z1000. I really love the bike and while considered sport, they did tone down the sporting edge on it. So make no mistake, it does not compare to a zx6r in track like conditions.
Having said that, the z1000 is quite capable, it would take you up to 80% of what a sportbike can do. If you skills can take you beyond that, then you will want to upgrade the suspension. I ended up putting zx6r suspension on mine & it is a totally diff beast in the handling dept.
As for power, the Z has more usable power down low on the streets than any of the middle weights. Howver, the zx6r mill is very powerful & its power to weight ratio is better than the Z, so don't expect to have a much faster bike than the zx6, cause it isn't. The Z makes about 10-15 more hp, but the z also weighs about 60 more pounds.
Despite all that, I still prefer my Z. The reach to the bars is comfortable, it has plenty of power to keep up with average guys on supersport bikes. And like you said, the looks are very much more aggresive & raw compared to the supersports...
Here is a pic of mine....
