I recently got the 800/400 pair for my bike. I have to say, I am thoroughly impressed. A part of my commute to work(which I've only done a few times now), is along a 4 lane 55mph highway. It does have a designated bike lane along the shoulder(about a full lane wide).
While leaving work the other morning, a coworker passed(and honked) at me. I asked him the next time I saw him, how far away he could see me with the 400R taillight. He told me he could see me about 15-20 seconds before he passed, and this is at 55mph.
The headlight, I haven't even needed to run at full brightness yet. 80% of my ride, while it is dark out, is on completely unlit roads and MUPs.
My only problem so far, is the tail light failed on me last night. After reading their website in the support section, it seems as though the batteries need to go through a few charge cycles before they reach full capacity. So that sounds like it was my problem, as the battery wasn't fully charged before I headed out(thinking I had plenty of time left on it).
Having this pair of lights on the bike, makes me want to ride more at night. It is quite nice riding along the river, in the dead of night, by myself.
I installed the 400R tailight and use it during the day when riding down heavy traffic roads. I have had comments by other riders as well as noticed cars really notice it and give me a wider berth than before. I will be communting more starting next week, and the I feel the early morning trips will be a bit more safer.
The best way to keep your batteries charged, if possible, is to just plug in your chargers right next to your bike. You don't even have to take the batteries off the bike that way - just disconnect them from the light and plug them right into the charger, right there on the bike. I just make a habit of doing it every time I use the lights at all.
One thing to watch out for, though, is that if you leave the lights hooked up to the battery for a long time, even though the light isn't on, it will eventually completely drain the battery. So...don't do that, like I did and find out the hard way. :-)