I owned a 1997 BMW Funduro for 10 years and I was the 260th person to join the on-line Chain Gang forum the following year. I agree with the comments above. The engine was very durable (pretty much bomb-proof) and smooth below 80 mph. Plus, fuel mileage was typically between 60 and 70 mpg. The engine was built and designed by Rotax in Austria, while the rest of the bike was assembled in Italy for BMW in an Aprilia factory, I believe. On my bike the only weak area were the electrics, which started to give me starting troubles after 10 years, so I traded it in on a new 2009 (built in June 2008) BMW (800cc) F650GS twin and have been very happy with that decision as the twin is even stronger and more refined than was the single. The 650cc engine was also used in BMW's F650CS, belt-drive single, which had the fuel tank at the right rear of the bike, while the area normally used as a gas tank contained a large depression with a fabric cover that could be used to carry small items. I think BMW called it a "funk".
I might add that around 2005-6 BMW shifted the building of the Funduro engine to a Chinese factory and then changed the bike's name to F650GS (single), which has caused some confusion with the twin when ordering parts, resulting in BMW then calling the F650GS 800cc twin the F700GS - but still having the same 800cc engine. Several other models were called F800S,ST,GS and GT, depending upon the chassis design. The GT was belt driven. All of the 800cc twins, as well as the 650 single have now been discontinued by BMW, which is likely why the 650cc single design is now available to other builders.
Anyway, if the new BSA Gold Star actually uses the old Funduro engine, that is a very good choice and anyone owning that bike should be very happy with its performance and durability - assuming that it is being built to the same standards as it was previously.