I'm actually a big fan of Water Wetter. Up until last summer when my engine started running on the warm side on the hottest days (due for a flush and water pump I suspect) my engine would warm up noticeably quicker in the winter months and would hold temperature very well year round. Heat transfer into my heater cores on max results in almost unbearably high vent temperatures. Been using it for about 13 years now IIRC.Sounds like water wetter and slick 50.
I suspect (just a layman's guess but makes sense to me) the improved heat transfer in the coolant passages closest to the exhaust valves aides in more quickly distributing heat throughout the cylinder head and the block, decreasing warmup time.