650mA is rated current not max current.
CREE XM's are rated at 700mA but can be run at 3000 with proper cooling. this turns a 3W piece into a 10W, so power is an important considering when running an LED at nonrated current, not to mention the 30k hour lifetime goes out the window, but this is an extreme eg. If you are talking about about a mere 10% over current on a small project however, you can expect things to pretty much behave as manufacturer intended.
In my experience a 700mA LED will take 1200 easily, with about 60% more light. (IMPORTANT: the 9 LEDs will use 46W instead of 27W if you used your current driver. If it cannot support this power, current will fall below and regulation will stop) lifetime sof the LEDs hould halve. If it is good brand, lifetime means gradual fading over time until it is more efficient to change the whole LED. Poorer brands will just die and open circuit. If you want to extend life, go for better cooling rather than undercurrent, because straying too far from rated values will cause the color temperature to shift also.