For Summer use, do you overheat with high R value pads?

"Grand Canyon, September 2014, on the river. 110F air temp. 100F ground temp where I set up camp (Brunton recording thermometer). I didn't sleep much that night."

In cases like that – as I mentioned in the last thread concerning this topic – it still doesn't matter (practically) if your mat has a high R value. Perhaps the R value would be appreciated since the ground temp is actually hotter than body temp. In effect you'd be cooler on the 'warmer' mat than on the ground. Thus, the answer to the OP's question would still be 'no'.

The thermal mass referred to is the ground, not the pad. Some types of ground will retain heat or change in temperature differently than others. The pad may insulate you from that, for good or bad, depending on the extreme planetary scenarios being discussed.
Me, I would avoid molten lava.

> Grand Canyon, September 2014, on the river. 110F air temp. 100F ground temp where I set up camp
Blimey.

Yeah, been there myself. Sand under cliff face, facing the afternoon sun. Slept until about 3 am on casuarina needles in walking clothes – no tent, no mat, nothing. Hot trip.

Cheers

The water bed will conduct the heat from you MUCH faster. Water beds come with heaters to heat the water so they don't cool you too much. You need one unless you have sustained indoor temperatures over 80 something degrees. There is a lot of water to heat and it takes quite awhile. Even when it's warm out they still conduct a lot of heat away from your body. This is all backed up with actual experience, btw.

A higher R value pad will keep you warmer. If you are too warm you can remove the insulation over you to cool off. If you are too warm after removing everything then the pad might be a problem. However, you will probably still be warm even if you were on the ground at those temperatures.

Also, having the "cool" ground conduct heat away from you is more uncomfortable that the air doing so. You get localized cold spots that for me are very uncomfortable.

The Neo air style pads may be more of an issue. I've never used one so I will have to defer to others for those.