I am not good with electronics, but from my observations some LED do have power converter that gets hot (ask me how do I know?), while my latest purchase - LED boards don't have any converter and I can touch them with no problem.
The wattage calculation is tricky as there is lot of salesmen misleading, but I added 4 of 3 W LED board into my ceiling lights and it is plenty. If you have meter- measure the W as I measured 15W lights to draw only 6W.
What is good about them, If you have big fixture like my old fluorescent, you can put a lot of LED panels to make it investigation room.
Also with LED you have a choice of colors. When color is personal choice, the bright white (I buy 6000 K) is the best color for reading.