Got back from my vacation and gonna chime in on the ROT66v2 that was awaiting me.
I am the biggest ROT66v1 fan ever. I had bought 4-5 over time, experimenting with different emitter options. I eventually settled on SST20 4000k + Lee Zircon 804 filter. It's my workhorse sodacan light that I use for hiking/night walking and ceiling bounce.
First impressions of the generation2 ROT66. It definitely feels heavier, and the added texture on the tube offers more grip-- feels like a grenade. The tube has way thicker walls since there's no battery carrier. The v2 is not much shorter than v1. In fact I'd say it's same size, with only difference being the taller SS bezel on v1. Not sure if I prefer the smoothness of the handle on v1 or the ruggedness of v2 yet. The heatsink portion of the light doesn't seem to be larger, but the fins are deeper. Hopefully the added bulk in the handle makes good contact with the emitters so some of the heat can flow down there.
The v2 has a side-switch that protrudes from the body, making it easier to find in dark. However, the side-switch button is not illuminated. That's a big minus for me compared to V2. I'm also not the biggest fan of the font style for the ROT66 name on its body compared to V1. I liked V1's smaller, sleeker font. In dark I know this is a non-factor, but it still gets to me.
My VTC6s rattle in V2, they do not in V1. That is a big minus for me. This rattling does not affect electrical contact, however it is very sensitive to being placed down on hard surfaces compared to V1. The light will flicker momentarily, but will still stay on. V1 will sometimes shut off if jarred too hard.
Aux leds are siginificantly brighter on V2 than V1. That's a plus in my book, because now you get the opportunity to adjust aux led brightness through anduril ui, to make it dimmer if you want.
Beam pattern between V2 and V1 (both running SST20 4000k leds) is more different than I thought it would be. V1 had a spotlight effect with a large, filled hotspot and soft corona leading to a dim spill, which I quite liked. V2 has a way smaller hotspot, followed by brighter, wider and more usable spill compared to V1. I think it's definitely the more usable beam, but I might prefer the larger, flatter hotspot of V1. I made a quick graphic to help illustrate the difference:
The 12 emitters vs 9 in the same amount of head is welcome. There's more efficient use of space there, and more available power plus higher sustained output. Always welcome.
Overall I think it's an improvement, but not a home run. I would like to see springs on both sides of batteries for a tighter connection. I might even try playing with longer batteries to see if that helps. I would have really liked to see aux lighting on the side-switch for super ease of locating in the dark. A lot of the things that drive me to the ROT66 are still here: stainless steel bezel AND tailcap: 7075 aluminum, 3x18650 form factor, and aux lights. I could care less about the Osram version as I enjoy the CRI and tint for a workhorse light, but I am now intrigued by the D18 a little.
Edit: I am now trying out the beaded optics, lanyard screw in, holster, and diffuser. The holster doesn't seem to be anything special, but looks serviceable. The ROT66 fits snuggly into it. The v1 didn't have a holster so this is a good upgrade.
The lanyard attachment is awkward because it juts out where I would normally place my index finger. It's not the most ergonomic, but I do quite like the new stainless steel plug that the lanyard screws in to. It looks nice when it fills the awkward hole that the V1 had if you never put the lanyard on.
The diffuser doesn't stay on the head of the ROT66, and just falls right off unless you're tailstanding for use as a lantern. Besides that one scenario it's totally useless-- which is okay to me, because really I only see it being used as a lantern replacement.
The beaded optics are nice-- really nice. Huuuge smooth and filled hotspot, with not much output wasted in spill, like you would see with frosted lenses over reflectors. The tint of the SST20 mixes very nicely with the beaded optics as well. In throw optics, the SST20 has a slightly warmer and greener hotspot compared to cooler and more rosy spill. This effect is very, very subtle, but with the beaded optics, you get an amazing tint that's cooler and more rosy overall. It's very nice.