Going by reviews the NOV-MU can only sustain more than 1000 lumens for 4 minutes, before a gradual decline to 600-700 lumens. 4 minutes may be long enough for some photography use cases, but not others. The RB9 can sustain 1,000 lumen for most of its runtime. Both will out perform the lume cube 2.0 which I measured at 650 lumen (far less than claimed), but at least it can sustain that output.
I haven’t measured it but I hold it in my hand while using it so maybe the heat sinking helps. I normally don’t turn it on for more than 4 minutes at a time to conserve energy so it just appears really bright to me whenever it is on.