I took one up to Stevenage.
If it's great handling you're after,get a Ducati.
If you want to improve the handling of your Harley,Progressive Suspension shocks and springs with some decent tyres like Avon Venom or Metzeler ME880's.
If you're thinking of buying a Harley and want reasonable handling go for a Dyna,avoid Softails and the Ultras. An ElectraGlide Standard handles surprisingly well for a 350 kilo bike with hardly any ground clearance and in the right hands (not mine) can be hustled along quite well.
I hav'nt ridden an XR1200 but a mate has one and he gets it well keeled over.