[funonone]

I have used all sizes and on a number of bikes, Ducati's and BMW's and the first thing you'll notice is turn in quickness. The larger tires (both front and rear) will effect this dramatically.
The 180 will slow you down and flickabilty will be harder although not unpleasant. Yeah, they look better and on a higher hp bike exit speed will benefit as the tire tries to spin and has a little more contact patch.
The front is also dramatic form a 120/70 to 120/60. If you are used to the high speed stability on regular highway riding, the 120/70 is the tire you want.
I have also found the the rear rim sizes dictates what tire to use. Although the 170 can be used either on the 4.5, 5, 5.5 rims the 180 wants a 5.5 . The 160 should have a 4.4 or 5 inch rim.
Hope this helps, or yeah, Don't buy those tires @ JC Whitney! Better tires are always worth it.