Hey Rollo don't let these guys sway you on to an antique 21. Personally I would never own one so it's not the best bike in my opinion. And that whole 5 hp more isn't much in the scheme of things. Hell I'm 20lbs overweight so if that mattered I'd just lose weight and more than make up for it. Never had a 21 pass me anyway so that little edge is for the less skilled. lol
The 21 was kind of thrown together by Honda, look at the calipers, they just used what they had on the shelf even if they had to mount them backwards. They got them right when they installed them on the 28. Look at the swingarms. I've never seen a single person try and install the 21 swingarm on the 28. But you'll find thread after thread of those mounting the 28 on the 21... what does that tell ya. How about the credit card ignition, that alone has had people stop and talk to me for half an hour. They'll knock over a 21 just to take a look a the 28 parked next to it just because of those two features right there.
Buy what you like and don't settle for less then the latest generation NSR just so you can have that whole 5hp. lol