Welcome aboard John and good luck on your search. What Rufus said is spot on.
If the Base/Pure/Classic you are looking to buy is new, the rear suspension may have not been adjusted for road use yet and could be on the shipping position, which mean it would be on the firm side. If this is the case, do mention this to the dealer so that they adjust it for you as otherwise it will give you the impression that the bike rides on the harsh side.
The B and TC have the rear suspension adjusted electronically.
Let us know how you get on and enjoy the test drive. All R18 shake a bit due to the gorgeous boxer engine and this is one of the quirks some people love or hate, like Marmite. As the bike breaks in and parts starts to mate, she will get smoother.