1, thermal management, they will both become hot in about the sime time period
2, max output —> SST20
3, autonomy (?) don’t know what you mean, battery life will be about the same since both versions deliver max 2,8 Amps.
1. I knew that SST20 geta hot faster.
2.I am asking because I saw ar fasttech that the SST20 variant has 650 lumens max.
3. Set on max mode which one will Haven the longer runtime until it shuts off?
2 - Yes, SST-20 will get ~700 at max on 2.8A, XM-L2 closer to 900-1000. Very little difference to the eye in reality, except that the SST-20 is much throwier as you already know.
3 - Neither. Both those drivers run at 2.8A max, so the drain over the course of one battery’s charge will be basically the same. The XM-L2 will probably gradually dim sooner due to insufficient cell voltage earlier since it has a higher forward voltage.
The SST20 should have lower forward voltage, and therefore will stay in regulation longer… so the runtime at 2.8A will be slightly longer, and the overall runtime will be slightly shorter.
SST20 throws farther (not that interested in that aspect), has less lumens than XML2 (700 vs 900-1000), stays a bit longer to max output, but it’s overall runtime is shorter.