OP: How much light do you need? A 200L is almost sufficient for me on unlit suburban streets and bike/MUP trails (neighborhood lighting nearby but not direct) and plenty for "be seen", especially on flash mode. My commuting set uses as of last year a 600L on the handlebars and a helmet-mounted AA-version 200L on flash mode. I don't feel the need for more lumens - the 600L provides plenty of light to see objects on the pavement and warn me of ninja joggers. The 140L-type taillight is visible for at least a 1/2 mile, based on overtaking another commuter using one and using landmarks on the local trail to judge how far away he was when I saw him.

I used to be concerned about spending more on the lights than on the bike (or at least the drive train or frame). Then I considered out of pocket expenses, co-pays, lost work/riding time, bike repair/replacement, etc... from even ONE accident or near-miss and decided I'm well worth the presumed increase in safety (my teenage daughter has seen my rolling light show in action driving past me when I was riding home and says it's "really obnoxious"), obvious behavior from overtaking drivers (especially when I was recently working until 11:30PM-midnight and what cars were out had no reason to change lanes unless they saw and were avoiding me) and peace of mind it gives family and co-workers that I don't have a death wish just because I commute by bike.