Done and +1 to the ranks of the K60 owners: me. Quick writeup on first impressions:
After playing with it for a little while, EVERY OTHER LIGHT I have looks dim. Even on partially depleted IMR batteries, which don't run the 5K level at full blast (I haven't had time to charge them), the K60 is VISIBLY brighter than the TK75 on fresh cells. The ring UI is so much nicer, and makes the K60 a surprisingly practical light: if you set aside the size, coming as I do from the days of much larger lights (eg various Maglites of considerable length), it's actually really quite useable.
Firefly mode is very charming - amazingly, it is dimmer than all other lights I have (various SF, Fenix, and an Olight). Perhaps this is my first true firefly light.. ironically, my most powerful as well. I know, right?
High mode gets really toasty, really fast: I was thinking gloves might be a nice accessory. But we are talking about the obvious here: a 42+ watt front end. You know what you're asking for if you decide to get something like this. This is not a light for beginner owners, just like the insanity-class hotwires (back then, 3K+ lumens) were mainly acquired by those with a familiarity of how to feed and tame the beast, or at the very least, were committed to learning how. That having been said, today's insanity class LEDs are much safer, and easier to operate than the risky hotwires of old. To put it into perspective, once upon a time, we were pulling a mere 3K lumens from over 120 watts of power. And once upon a time you needed HID to get anywhere in the realm of 3K. Quad core LED meant 100 lumens (Luxeon V), not 5K. And I was just telling the story of the charming 10W Welch Allyn HID capsule in the Mag2HID - a mere 500 lumens!
The key advantage with today's LEDs is the ability to dial down the power. Oh, I remember we had PWM incandescent dimmers, and I used them too. They were brilliant, but today's LEDs offer much more consistency and control over power outputs. A firefly mode and a 5K mode in the same light? Up till last week I wouldn't have believed it.
Thank you Acebeam: great job on the K60. For a light with so much power, it is surprisingly practical and useable as well.