Have both RMK's, pro and non-pro. RMK with cooler can still get hot at low speeds and poor snow conditions, but does not get as hot, and not as fast, as the pro. I can't say one cools faster than the other. Can't say I ever overheated either of them, always get them in the snow first. RMK with cooler does take longer to warm up, especially from dead cold, since the bypass to the front cooler is always active, not thermostat controlled. Never seen much difference in cold shock temps.
Anyone who gets a SKS would be well advised to get scratchers, especially with the 2.6 or 2.4. Not just for coolers, but also for track - the every other window clipped tracks keep weight down, but don't like poor snow going up or down. You will get windows wear at poor snow or high speed. FWIW.
