Mike,
The Mackie powered studio monitors are NOT a good choice for road use. They are not built to take travel well, and honestly, I bet you'd overdrive them in a live performance.
If you can handle the weight - the 450's are soooooooo sweet and have the best horn displacement I've heard in a portable.
If you only need small to moderate volume - try the Yamaha pc speakers that George Kaye sells (I forget the model) I have a pair, and my FP3 sounds amazing through them! Tiny sattelites, and a small subwoofer put out 80watts, and sound great!
As to the kn6500 vs SD1 real - my money would go for the 6500 because the os is more complete. I still believe that the SD1 needs some factory tweaking !
Have you even tried the 9000pro? It's my top fav for an all in one these days. Great mic processor, incredible piano & organs and the best effects section on the planet - 12 dedicated dsp's. Awesome.
Hard drive, lights, xlr mic in ....... sweet.