L&M Solo on the helmet? You said you were running the other light on the bars and did not specify about the Solo. I repeat, why would you need anymore than what you have?

I got the L2D CE Premium Q5 because I do road riding and prefer the whiter light. Go for the Rebel version if you want a color closer to Halogen, or so others have said. No personal experience with the Rebel. I prefer AA's because I already had a charger and batteries and wanted at least a 2-hour runtime. You could get by with a 1-battery version for your short commute.

I prefer a helmet mount over a bar mount and now have both. It is nice to see where you are turning, street signs, and the computer and looking down to see which gear you are in. No negatives to a helmet mount for road riding as far as I can see and if I only could have either the bar or helmet I would go for the helmet.