Latex tubes are not recommended for use in our clincher wheels. Latex is very inconsistent in comparison to butyl, and doesn't hold up as well in all of our internal testing.
Our wheels are provided with either ENVE cloth rim strips or tubeless tape (model depending) that cover our spoke holes to work well with butyl tubes in the clincher format. Use of latex tubes in the tubular version, however, work perfectly fine. The tubular completely surrounds/supports the tire, whereas in a clincher tire, the tube comes in contact with both dimples in the rim strip from spoke holes, and edges of the inside of the tire. In essence the tube inflated inside the tubular tire is always round or at least elliptical in shape whereas in a clincher the tube shape can become deformed by the edges of the tire/rim contact point as well as the spoke holes.
There is no specific temperature found for when latex tubes become unreliable. The inconsistency and unreliability of latex tubes come more in regards to variable wall thickness of the latex tubes (ranging from 2mm thick in some areas, to less than a half a mm in others). Similarly, the way in which the latex tubes are sealed together and joined at the seams can be very inconsistent. With such variability in a tube - often we see wide ranges of variability in latex tube durability. This variability can be examined by simply pumping up a latex tube outside of a tire. The latex tube inflates with varying degrees of pressure throughout the tube (bubbling on some parts, while retaining the "tube" shape in others). Compared against a butyl tube pumped up, outside of a tire, however - it's easy to see why butyl is a much more consistent and more reliable choice.