Well, wait for it.... They basically ARE the same for all intents and purposes (assuming same speed, latency and voltage). Add Ripjaws and Ripjaws X to that as well.
Hell, any name brand RAM, when comparing the same speeds, timings and voltages, are identical performance wise and virtually identical quality wise, too.
Just get whichever one you like the looks of better.
As to the heatspreader question, I'm not sure. I'm guessing it can be done, but just get a kit that you like the looks of the best and go with it.