I know this thread is a little old, but for future readers: “Yes, this works great.”
I swapped in a set of LH351D LEDs on my Seeker 2 Pro. I went with high CRI 3000k warm white (bin code SPHWHTL3DA0GF4VPP6). The well-known “DA0GF4RTS6” SKU is 5000k, and would still be dimmer than the XP-L2, which I knew going in. The “DA0GF4VPP6” at 3000k is in the same quality range but there’s maybe a 15% hit to output going to the warm white dome vs. the 5000k Samsung chips, according to the datasheet. The reflow was fairly trivial, though there is really not a whole lot of length on the wires to re-attach them once the MCPCB is back in the light. The solder on there is lead-free and the metal PCB really, really eats up heat given that it has to be reassembled in contact with the body of the light – needs a good iron. I considered the SST-20 in a warm white, but have one in a 4000k EagTac D3A and it’s a bit too much throw for my taste in this light.
In terms of sizing and alignment with the lens, the LH351Ds are really a 1:1 replacement for the XP-L2s. The beam is beautiful, floody but still with a decent broad hotspot since this is mostly controlled by the stock TIR lens. It might be a tiny bit less defined at the edges. I looked into other lenses, but best I can tell it’s custom – there aren’t a whole lot of 26.5 mm diameter triples out there. Also, the white alignment / backing piece has pins that hold the PCB into the flashlight, so it would take a bit of hacking to keep the same mechanical design with a generic optic.
For me, the 3000k is perfect, sort of late afternoon sunlight. There is a noticeable dropoff in output, but honestly it’s still plenty bright for any reasonable use. Comparing to another OLight (the H2R Nova in NW), it’s similar in output, I’d say the modded Seeker 2 Pro is still a bit brighter. So, probably in the 2000–2500 lumens range – it’s difficult to be sure given the difference in colour temperatures. The colouring is night and day vs. the H2R. Way warmer and more pleasant, but also the CRI difference is huge – reds really pop.
If I had a line on TIR with a broader spill I’d probably go that way, as I’m a sucker for floody optics… but as a general purpose task light this is in a really good spot. Standard complaints about the OLight batteries aside, this is really a grail for me on ergonomics and the pleasant / useful output with the swapped emitters.
