I'm not familiar with the FZ8, but I know the modern Triples are outright amazing with the right operator. I'd imagine parts availability and dealer support is going to be better with Yamaha though. Triumphs (race bikes so apples and oranges) still have engine issues from time to time, but nothing like the oil leaks of olde. I'd say it would just be more expensive to maintain the Triumph when something goes south, but they're usually very capable. The Yamaha is probably going to have a larger aftermarket as well.