The cleaner engine "argument" is a good one, but there are far cheaper and effective ways of doing this such as fuel aditives like "redex" but with the FZ8 being pretty much out the box age wise it won't suffer from a lack of performance through carbon build up for quite a few thousand miles yet. It's a prety bullet proof engine desighn based on previous R1 and FZ1 models, I supose really it's down to the individual, the bike will run on premium, but there is very little to gain from it, if anything. A cleaner engine? yes ok, but at what cost? higher engine wear due to incorect timing? But thats just speculation, what is fact is yamaha have tuned the engine and ECU to run prefareabley on standard rather than premium fuel.
Why would they do that if there is a gain to be made by tuning it to run on premium? Easy, running costs! The FZ8 is desighned primarily for the european market, to go head to head with the euro sales leader, the kawasaki Z750 and Z750R. One of the big factors in europe is fuel costs and MPG figures. if the FZ8 was tuned to run on premium this would be seen as a negative sales point rather than a posertive one.......Sounds a bit daft but with the cost of fuel in europe it is a big issue, especialy when you take into account alot of people are actualy switching to bikes as there predominant comuter transport due to high fuel prices.........This is the sting in the tail however, the FZ8 isn't actualy what you would consider a "standard" choice for a comuter bike, 125cc-600cc is the usual choice but that fuel figure mentality has spread to encompas even some of the 150bhp+ bikes coming onto the market currently.
It would have been nice to be given the option by yamaha of simply having them offer two ECU fuel maps, one for regular and one for premium with a little more grunt but I don't think that made the budget LOL maybe in future Yamaha dealers could offer a remap service to those who want to fun on premium fo a little extra performance? It could happen if enough people ask for it! I'd certainly be one of the first in the cue