I think you have to look at this as 2 topics. Do you gat YES w/ maintenance or the YES warranty only.
If I remember correctly, the YES without maintenance costs $620 for 4 years. You'll need to check on the actual coverage time, because most "automotive" extended service plans (warranties) count the 1st year, which already includes the manufacturer's standard warranty. What that means is the 4 year warranty might only be getting you 3 additional years of coverage.
If you don't think you're going to have cash in the bank to pay for major repairs, then YES might be a good idea. It's a lot like having health insurance in that most people can't afford to pay for a $50,000 hospital bill or even make payments on it. but they can afford to pay $100 to $800 for insurance. If you're low on funds, you might ne able to make payments on YES that might be lower than credit card payments for any repairs.
As for the YES w/ maintenance, I say NO. The fz6r isn't that complicated and niether is the maintenance. You can learn a lot online, like through this forum, or have a friend show you how. You'll need to invest in some tools and time, but they'll last you for a lifetime.
I got lucky. My local Ford dealership has a tech that likes working on motorcycles, so they did most of my 4,000 mile service for $20. I said most because I brought the oil & filter and I chose not to have the spark plug gaps checked. It never hurts to ask.
BTW, I'll be buying the 4 year YES, but I'll call a couple of dealers to negotiate the price.
One thing I forgot to mention, most warranties are transferrable in case you sell it the bike, if not, they refund the unused portion of what you paid.