We recently had a couple of customers use our suits on a trip through Church Cave, in Kings Canyon, California. This is a great sporting cave, with plenty of squeezing, crawling, climbing, and other fun; ambient temperature is in the mid-50's F; thanks to the ongoing drought in California, most of the normally-wet passages were dry.
In this cave, one of the Salamander cavers decided to go with a full-sleeve polypro underlayer, with the coverall sleeves retracted; another went with a lighter t-shirt underneath but full sleeve coverage. After doing a seven-hour through trip, both reported being happy with the temperature and protection tradeoffs. The hiking-pants mode came in handy, too, for the hike to and from the cave.
By the way, we'll be bringing our suits to Karstorama June 26, 27 & 28 -- please stop by our booth to check them out in person and try one on; we think you'll like what you see!