I already had an older bigger 700 lumina and I was wishing I had a second light for mtbing at night. One surprise even though this is the micro version they both use the same mount so I could interchange them if needed. For commutes just the one light is fine, but for trail riding having a helmet light and a bar light makes a HUGE difference. Plus then you always have a back up if one goes out or your buddy with the cheap import light that melts his helmet needs one to make it back to the parking lot. I use one light on low beam climbing up to the top, then put both on high beam for the descents. If you need to justify your purchase increased visibility and safety is well worth it. Plus if you ever have issues niterider has great customer service.
Have this on my helmet and a Lumina 1100 on the bars. Usually run it on low or medium setting unless bombing bumpy trails. People coming the other direction shield their eyes. I love when that happens.
Very light. Bought the optional helmet mount which works great.