Welcome, Wanderlust! Others around here who know more than me can chime in, but there are quite a few updates that happened in 08 that makes it worthwhile looking for the newer model...particularly the upgraded crankpins and oiling as well as the DDFI 3.
This is from a post about the upgrades to the Uly for '08, which I assume are the same for the other XB12 models:
The timer cover is eliminated, as the engine is now crank timed from a new crank position sensor, which eliminates the need for manual timing, reducing maintenance costs. The ECM actively monitors and adjusts timing based on driving environment. The new sensor makes 30 reads per revolution, compared to the previous two reads per revolution, for more precise control of fuel mapping and timing to conditions.
More Robust Crankpins-
* The size of the crankpins is increased to 1.50 inches from 1.25 inches.
Oiling System Upgraded
* A higher-output oil pump supports oiling to the new crankpin area. The new pump is driven off of the crank, a design based on the Buell XBRR production racing motorcycle.
* A new eight-row oil cooler offers enhanced cooling performance.
* All oil line ends are now equipped with Jiffy-tite fittings.
New DDFI 3 ECM (Engine Control Module)
* A new ECM with increased computing capacity.
* DDFI 3 actively controls and monitors the TPS (throttle position sensor), IAC (idle air control), and timing. DDFI 3 automatically zeros the TPS and adjusts fuel metering for smoother idle, eliminating service intervals and reducing the cost of ownership.
* A new progressive throttle cam and new throttle cables provide smoother throttle input from stops, and less rotation to full throttle
