I've got two sets, one slightly older than the other. I've found that the newer one has a slightly tighter beam pattern. To be honest using them both together probably provides more light than I need to ride off road at night. I rode happily with only one set on helmet for a couple of years.
Even when I only have one set it makes my buddys Exposure Diablo look wimpy.
I have used Hope's awesome after sales service to have the cables and LEDs replaced in the older unit (it was four years old ar the time) and they did this free of charge.
A couple of pics with one bar mounted and one helmet mount.
Medium setting. (equivalent to one on full in my opinion)
For reference, the telegraph pole is about 50 metres away, the reflective corner bollards about 150 metres.