In my experience going from mega lumens to a well-engineered dynamo light (Son Edelux II) was no problem - yes it might light up slightly less of the buildings around you and fewer road signs 3 miles away, but the focus and spread is excellent, plenty bright enough for unlit paths and lanes. It's also super well positioned/angled for oncoming drivers etc, having seen it myself from the other way!
In my experience going from mega lumens to a well-engineered dynamo light (Son Edelux II) was no problem - yes it might light up slightly less of the buildings around you and fewer road signs 3 miles away, but the focus and spread is excellent, plenty bright enough for unlit paths and lanes. It's also super well positioned/angled for oncoming drivers etc, having seen it myself from the other way!