Thomas, unless you are doing “something” else in these cases, I am pretty sure you may be overdriving to some extent the LH351B emitters in such host. Don't you think?
Oh! Well, I see the 21700-C8F's output isn't as impressive (versus 18650-C8F).
FWIW, the C8F-21700 FET-driver is somehow limited or at least not as powerful as other FET drivers. It's quite hard to override a certain "threshold" of about 10A with this driver. Even with a Samsung 30T/40T you will not get that much above it. In terms of the LH351B it appears it can easily sustain a current of 3 - 3.5A, even though it's supposed to be driven to Imax = 1.5A i.a.w. the datasheet. Using the Sofirn brand battery (which appears to be a Lishen LR2170SA cell) the current for all three emitters is probably 9A or less.
Olight mods! So I put a LH351D 4000K 90CRI in my S1R Baton II, and LH351D 5000K 90 CRI in my S2R Baton 2. These perform really well with the stock optics! I will actually EDC some of my Olights now…
Has anyone tried a single LH351D in direct drive? I’m planning running a sliced dome 5000K on a Bistro FET+6+1 TA driver. The Vf is not that low so I hope it will be OK to blast a few FET turbo runs now and then.