No - you can push start a very very very dead FZ6...this has been proven time and time again. The \"push-start\" should be taught in the MSF IMO.
The OEM battery in my 2004 is still going strong after numerous winters, lots of abuse, and without ever being on a tender.
your very lucky! as far as the push start it will eventually take its toll! As far as your battery biggest thing is how much you ride also. Some batteries you just get lucky but most do not!