Mostly the 6v3w standard. Give us another 2 watts and we could put out even more light. It does seem that everyone's hesitation, mine included, was that a battery can supply more power than a dynamo these days. Also, flash/strobe mode would be nice for us NY'ers where it is standard. You almost never see steady lights here.

And in the battery vs. dynamo discussions, nobody has really emphasized that in reality the Cyo Premium will out-light the battery units. It is always lux vs. lumens, lighting the trees vs. lighting the road, and other arguments. But the bottom line is that the Cyo just completely blew away my other. It isn't subtle.

Let me add too the drag factor. It just isn't noticeable. I can turn it off and on, which I did last night to test, and didn't feel anything. Admittedly, the dynamo light was just one of many improvements to the bike that I did this winter. It rides much better than it ever did.