Well I tested the blue & green with the driver powered from just over 9v worth of batteries wired in series (so that the output from the driver without load was just over 9v & within the safe range of the LEDs) & they lit fine - green left quite an after image in my eyes... I didn't actually measure what the output voltage was when the LED was attached though.
Although the spec sheet of the driver says that 15-24v will do for 3 blue/green LEDs I would be very apprehensive of applying this to a string of LEDs rated at a maximum of 11v? Is this really safe? Or will the voltage coming out of the driver not actually be anywhere near 15-24v when the LED is connected?