What else can you tell me about the BC30 ?
Based on what I saw on the L2D specs, the BC30 will be huge performance improvement. Your L2Ds give a max output of 215lumens. The BC30 does 1200 lumens sustained with 1800 burst (with the included remote). I ride with the 1200 mode almost always at night, with the flashing mode during the day. The flashing mode is a bit of a slow interval, which doesn't gain much attention, but it also doesn't blind people as some quicker flash modes can.
As for planning on keeping it at 500 lumens, I think once you see the 1200,you won't want to use a lower mode unless you are low on battery power. In than case, spend $30 an buy a 4 pack of 18650s for swapping and you shouldn't run out of batteries on most rides. The remote button is pretty cool to flash when you need to get extra attention quickly.
The light is very sturdy and well built. It's not an ultra compact, but it does not get in the way on the bars. the mount is easy to remove and the light pops off separately too.
You'll get about 1.25-1.5 hours on two 18650s...the light has an low battery indicator. Simply pop in a couple more and you'll reach your desired 3 hour output requirement. Bring a second light as backup too!
I recommend bright red flashers ...I ride with Metrolights on my helmet and seatpost (2xAAA each). A police officer even complimented on my visibility tonight!
The BC30 is more flood than throw, but with a helmet light you can achieve throw. I believe a two light combo is ideal for night riding that involves any type of frequent turns or glances when a bar light won't illuminate where you are actually looking.
have fun night riding!