That's one of the four sections of my room lighting.
Heatsink is 10.5cm x 5.5cm with thick fins on the back.
It has 3 white leds (3.2W each) and most of the time these are all i use.
The others there are 1W in RGB but only used to tint the color a little.
So i estimate it's dissipating at least 10W
It gets hot enough that you don't want to hold it for more than 5 seconds or so, probably around 50degC.
Which is within the specs of the leds.
The entire lighting rig has been my room lighting for 4 years now and no leds have died.