I ride right with my tenner's worth all through the night Cranky in unlit countryside. Rarely do I have both on full power. I guess I just don't share your night vision problem. Maybe you are getting a bit old for this sort of thing ...Err ................. to get a much better light? Eg Exposure Max D. It's as good as my car headlights. The only thing better would be x2 of them.
If you need car light power at 17mph then I'm not sure you should be relying on them at 70 mph. Just sayin'