Well, got the B&M SuperCooler installed last week and had our first chance to tow with it this weekend. Since we've had it installed temperatures here in Seattle have been unseasonably mild with highs only in the mid 70's so it's not really been an acid test but the results are still amazing.
Just driving around town transmission temperature is lower by about 25 degrees. That is with the outside temperature in the 70s the gage is reading ~125 at the sump. I might worry about that being too cool except the sythetic fluid extends the working range both on the hot and cold side. The cold weather performance was demonstrated last winter when the temperature up at the ski hill hit 10F for the high. Stop and go traffic shows even better performance with the SuperCooler. What would have sent tranny temps up around 180-200 are now peaking at around 150.
Trailer towing showed the biggest difference pre/post cooler installation. Admittedly it wasn't that hot this weekend and Snoqualmie Pass isn't a monumental grade but the direct comparison with a trip earlier in the year leads me to believe the "reserve capacity" provided by the low temperature bypass design of the SuperCooler really does work. Last spring we pulled the Pass with a lighter load and the temperature at the summit was 40 degrees. The tranny temp peaked at ~200F. This trip the outside temperature at the Summit was 60 degrees and the temperature peaked at ~160F.
Oh, one other thing I noticed is that trailering on the flats where we'd previously seen the transmission run ~25 degrees warmer than normal we're now seeing virtually the same temperature as when not towing.
I'll give the B&M SuperCooler a two thumbs up