Since alkalines can’t maintain voltage under load, I’m sure it will fall out of regulation much sooner. An NiMH AAA can handle the ~700mA load from this light without a problem, but an alkaline gets pushed to its limits and wastes a lot of its energy content in heat at that load. It also will be at high risk of leaking after such a hard drain.
Here’s a test of the similar Olight i3e EOS - excellent regulation on NiMH, but only 7 or 8 minutes before it falls out of regulation on an alkaline:
On the other hand, alkalines have pretty good capacity at low loads, so multi-mode lights or low output lights like the Fenix E01 can stay regulated for a very long time when producing only a few lumens.