Previously I ran the 3W LED Quartets at about half the maximum current, heat dissipation worked fine with some big exposed pads on the PCB. With the new modules I wanted to run them at their full specified current of 700mA but that turned out to be a thermal nightmare. I would have to add a huge heatsink to the LEDs in order to keep them at around 50°c.
So I have two options, stick with 3W LEDs and limit the current to 400-500mA or go with 1W LED chips.
Considering a low price point while still being a very usable thing is my main selling point for this project I will probably switch my design to 1W LEDs and do some testing if I can get a way with exposed pads on the back side of the PCB. If not I'm thinking about attaching some thin copper shims to the back, you can get them for around 17 cents for a 20x20x1mm one (at qty 50, see the link below).