DrP, I run one of the 2-modes with a Turboferret 4-cell battery pack, works brilliantly. But I'm not sure if those are still available.
Both of mine are 2-mode, and yes the low power mode is too low to be very useful for cycling. Or so I think, it's actually barely less bright than the lower end Hopes or a Joystick and some people like those. That's the biggest failing of these though, 5 modes is too many, 2 mode is just right but not if the modes are wrong, I basically only use mine on full power.
And yes, they're ace. Better than most expensive lights. Durable too, I slightly broke one by dropping it right down 3 flights of stone steps but it was easily fixed, just needed a new front pane which I made out of a CD case 😉 It never went out.