Kevin You failed to mention the year. The early 99's and older had a very weak alternator, and the lights were always dim at idle. Your battery may also be going south, aggravating the problem. The brake light draws a lot of current,also adding to the problem.
If the '07's are still wired up the way my '01 was, then battery has nothing to do with headlight power...
The RE's are wired up for DC/battery power for everything BUT the headlight, which is direct AC from the alternator. So, when you come to a stop, and that well-tuned RE settles down in to that super-low tickover we all love, your headlight turns into a votive candle at best. Which really sucks when you're say, riding around lost in the Texas panhandle at night and trying to stop at intersections to see the street signs, but then can't see anything because you've stopped...
It's little things like that which motivated me to re-wire so that the headlight was DC/battery power as well.
I find it really strange that the bikes are wired this way, especially the older kick-only, points ignition models. Usually batteries were only put on these bikes for the express purpose of having bright lights at all RPM's.