I did an interesting comparison today:
Test Setup:
- SolarForce L2 host (little customized) used for both P60 pills for comparison
- two P60 pills - flattened pill top, both with a FT 6x7135 2.1A Nanjg, 22 AWG silicone, little dab of AS5
- identical parts for each P60 drop-in (SMO reflector, etc.)
- Samsung 25R cell (overkill, but should get max amps)
Test Comparison:
Results:
- XM-L2 U2 4C/aluminum: 2.12A tail, lumens: 578 @start, 547 @15 secs
- XM-L2 T6 4C/Noctigon: 2.13A tail, lumens: 626 @start, 605 @15 secs
Conclusion:
Well, two variables: the LED and the MCPCB, but the IOS T6 is ~10% brighter than the U2. Both beam tints looked about the same, but I did not compare side by side yet.
So, is the FT U2 4C really that worse than a T6 4C? Hhmm, you'd have to look at other test data comparing copper (direct thermal path) to crappy aluminum. According to Match's tests (https://budgetlightforum.com/t/-/16621), it should account for ~6% difference I'm guessing at this amperage of 2.1A. Possibly in my simple test, maybe as high as 10% with variations, then you could only conclude the listed U2 4C is in fact a T6 4C, or maybe worse, a T5 4C? Match did use a 20mm SinkPAD, so could be characteristic differences in performance in this range of amps.