You have in your post that you are ordering 4 royals, is this just to play with and see if you like the color effect? (a good idea).
If you do this, don't put the thermal epoxy on the LEDs you might potentially swap out.
Start them out by using toothpaste as the thermal compound (no joke!) and just tape the LEDs to the array (tape across the solder pads). Test it out for an hour or so. You can also use cheap thermal paste for CPU's. Once you've decided what you like, wipe everything clean and then glue them on with the epoxy.
Otherwise you'll have heck removing the 4 you want to change if you do want to change them.