Dinotte Mountain Bike Light System

I've researched mountain bike light systems for 24-hour adventure racing and have decided on a Dinotte handlebar and helmet package. I have the choice of a package deal of an 800L bar light with a 400L helmet light or a dual 400L package - I would put one on the bar and one on the helmet, although I suppose I could put both on the bar and find a quick release bracket for my Petzl headlamp and mount those on the helment (I haven't heard of serious racers doing this though). The dual 400 is about $70 less, weighs less and is obviously smaller/better profile but I have no idea if sacrificing the 400 L is a big deal or not for mostly two-track night riding, with some technical single track. Any thoughts?

Also thinking about using a a 2-cell battery on the helmet, which would last 2.5 hours at 100% power or 5 hours at 50% power, and a 4 cell battery with 5 hours of power at 100% or 10 hours at 50%. Maybe just run the helmet on high when the biking is dicey. Could have 10 hours of biking at night I suppose. I appreciate any thoughts.

I have a 400L that I use on my helmet, it is great, recently changed the lenses to have more flood. This really helped as the spot lenses had great distance but were narrow.

I normally run the 600L on the bars which really lights things up. Last ride my buddies battery died so I lent him my 600L off the bars to finish the ride. Running only the 400L on the helmet with the flood lenses didn't seem to loose that much, but this was on tight and twisty trails. Perhaps on fast wide open trails loosing the 600l would be a concern.

So for 24HR races when you don't want to be carrying extra weight I would opt for the dual 400L. Run one on the bar with a 4cell battery and the other 400L on the helmet. If you use a camelback I would opt for a second 4 cell and carry the battery in the camelback. With no camelback I would opt for the 2 cell battery to be mounted on the helmet.

Should you really want more light. Wait about 1 week as I hear new lights are in store.