First off welcome.. second... I would never buy a second hand sport bike (but that is just me)
What kind of riding do you LOVE... cruising and "sport" cruising are as different as the Busa and a Harley.. I am torn between the 2 myself.. nothing like cruising a big lazy bike down the road or tearing up bits of asphalt with the rear tire as you boil down a twisty road..
I have no idea what your bike is worth but I doubt trading it for an old sport bike is in your best interest... sell it outright and then start wheeling dealing on a "new" 09-10 busa (just my opin)