I made some back-of-the-envelope calculations with the help of Cree's PCT, and it turned out the SC600F III Plus didn't normally drive the LED to its maximum specified current, which is 3A, but rather stopped at around 2.2A, which suggests the 1800 lm figure quoted by ZL was achieved at ~13.2W LED input (merely 3W above the 2nd gen SC600). This one, however, seems to be driven at the full range of the specified input current, thus pulling some ~17.7W (not counting electric losses), which is roughly a third higher than the previous gen. This doesn't mean the light itself will become hotter—its thermal envelope is believed to be the same—but rather that it will become hotter sooner. But, at the same time, it will produce more light at the same temperature, as well as having a higher maximum. So it's still a win, but there's no sense upgrading from the III Plus otherwise... unless you really want that programmable UI, I guess.