Hey Matt,
though not a 450R owner, I enjoy a gentelmanly drool over the machine from time to time.

Setting up a suspension definately has a try-and-ride routine, but I think many would agree that even before that process has begun, setting the 'race sag' should come first, since it's dialing-in will be the basis for how you end up adjusting the forks and shock dampening.
I'm not sure what the manual says about the 450, but for the 250 I think it calls for the rear shock spring pre-load strength to be set up so that the bike will drop anywhere between 2.5 to 3 inches when you sit on it (fully dressed in riding gear). Making this important adj. puts the suspension in proper relation to itself, so that you're not just using the first inch or 2 of travel (which might be your case right now, seeing as you weigh in lighter than the avg. rider weight Honda chose to set the 450R up from the factory)... or the reverse, if you have a person that weighs in above the factory setup weight (say 200+) then they well need to strengthen the rear spring adjustment, so that the bike doesn't drop so much when they sit on it.
Set your sag first, then go out and ride. By doing the sag adj. first, you definately set yourself up to use the entire suspension travel rather than just a portion.
Kudo's on your bike choice!
You gotta love the 450R. Someday maybe I will love it from the rider's perspective rather than the on-looker. We will see.
Good luck to you.
-matt