A lot of great information has already been posted, being late to the party i have not much to add
The specs of the HiveLD have been stated correctly with the default maximum output current being 1 A and the possible maximum that can be configured through the setup being 1.2 A. With the thermal monitoring at the default value, the driver will reduce the output after a longer runtime even at 1 A in a Haiku, at 1.2 A this will happen sooner of course. This will keep the LED and driver below any critical temperature level.
It is true that the low output relies on PWM below 12mA (which equals brightness level 3 of 21), while all higher brightness levels are constant current. Brightness levels 4 and 5 can show some instability (flicker), that can be noticed when you don't move the light. For those looking for very low moonlight output or non-PWM output at low levels understandably this is not satisfying but it is something that i could not overcome with the current driver hardware, but i am looking for improvements for the next revision of the HiveLD-S.
The HiveLD works with all kind of cell types (2xNiMH (Eneloop), Primary, LiFePo and Li-Rechargeables). If you want to take advantage of the low battery reduction you have to set the right chemistry in the setup though. Because of the lower voltage level and thus the higher input currents for i. e. primary cells, the maximum output current is limited to a little below 1 A with those chemistries. You basically will need a Li-Ion rechargeable to reach the 1.2 A.
Again thanks all who have already collected all the detailed information above!