Jags, I don't think a SON is going to make more power than fresh batteries. What you see on the road depends on the power of the LED and the optics.
The best optics ever, the first series Cyo R (the second series isn't as good; they screwed the pooch), got a bit better reach than you have by focussing the light very tightly and cutting out the useful sidespill. That can land you in the ditch if you ride on the limit in the dark. The Cyo for racers, without the reflector, has even better reach, at the price of zero sidepill and long dark patch in front of the wheel, worthless on our roads.
All these things are compromises. Batteries bring more compromises. I wouldn't be surprised if Cateye sacrificed a little light on the road for longer battery life.
I can tell you how good a really good bike lamp driven by a SON is. If you cast your mind back to when VW Beetle electrics were 6V, that's the amount of light a Cyo R/SON combo throws from a relatively low speed to a relatively high speed. It's probably a bit less light than a modern car lamp throws on dim. I also have the Fly E, which has the same optics as the Cyo, but now the second generation (cr@p) type with the hotspot "feature", which is effectively a constant current device, driven by the humongous 36V battery for my motor, so I can show you what light it throws at maximum power and efficiency. See
http://coolmainpress.com/BICYCLINGbuildingpedelec6.html How does the lowest, traffic setting, shown in the dark of night, compare with what you saw? Is your lamp's throw wider or further or brighter or more even on the ground? Any of these would be an advantage worth having.
"the son dynamo set up was quarter as good again" -- This isn't likely. It would require 60% more power/better optics. I'm sorry to have to say that you've probably already arrived at that breakpoint where every doubling of the price of your lamp system will halve the (already small) increment of improvement in light cast that you received for the previous price doubling. (That's another reason I'm doubtful about the claims for the BUMM Luxos lights Dan wants me to buy first -- they're just not expensive enough!)
A point comes, on lamps sooner than on most other components, where you have the best you'll get without spending several times as much money to get a modest improvement. On lamps that point has recently been jolted upwards by the switch from halogen globes to LEDs and the surge in their power and advances in their cooling, but now we're already back to the more common marginal improvement rule.
From manufacturers, exaggerated light throw photos are the norm rather than the exception.
Andre Jute
