Just added an update to the top of the OP regarding the wattage rule of thumb along with my thoughts on color temperature. Here's a paste of it...
"When searching for LEDs that are comparable to the incandescent bulbs they are replacing, the rule of thumb that I use is 1:5, i.e. a 3W LED bulb will give you roughly the same lumen output as a 15W incandescent bulb. A panel that focuses all of the light where it belongs should beat this a bit... perhaps more like 1:6 or 1:7. So a 3W panel might get you the same output as a 20W bulb or so... maybe.
Also... if you want incandescent color temperature, i.e. if you want the LEDs to look as close as possible to incandescent bulbs in color... look for units in the 3200-3500K range. 6500K is more like "blue white." I have one that is 4200K. It's not too bad, but it is noticeably "bluer" than my 3200K LEDs and incandescents.
As always...
YMMV"
:)