There was a change to the Lumintop drivers that lowered the runtime on High to 30 minutes instead of 1 hour. Im not sure why, my guess is it was caused by increasing the output of the highest mode.
During the Worm Era, the drivers were regulated and more efficient, like in your Jetbeam. There is a thread about the change in the Lumintop drivers in this thread.
But I still think the Cu Tool is a classic worth buying.
changing LEDs changes output, not runtime, or regulation
fwiw
my copper Tool w sw45k makes 77 lumens, and on the same battery my JetU w Optisolis 6500k makes 72 lumens. The other modes are also similar between the two lights.
I much prefer the Tool because
it can clip to a hat
it does not have last mode memory
I prefer a tailswitch to a twisty
If you want a copper twisty, I highly recommend the Maratac aaa CU
.
To me, High CRI is THE most important thing, and from an AAA light, Im happy at 20 lumens and I dont expect to use them at 100 lumen levels
The Jet U driver runs flat regulated on High, which I concede the Tool does not, but the Jetu does not come in High CRI, does not clip to a hat, and I dont like memory. (because I forget, lol)