@ IanB
Do you notice the extra insulating capacity of the Exped to the extent you could use a lighter weight bag, compared to a mat without insulation?
We seem to compare the raw weight of mats when there is actually more to it than that in terms of performance, particularly with regard to insulation and how that would affect choice of other equipment.
The Exped is noticably warmer than a thermarest, both a base camp model and ProLite 4, and much comfier. In summer I’ve used it with a Mont Bell UL Down Hugger 7, (this bag has hardly any down) for high alpine camps, and it definently works at keep ground chill at bay. It’s also been used for glacier camps, although the better half used it, no complaining in the mornings so can safely assume it works, she was using a 3 season Mountain Hardwear down bag.
I went for the PAC mat based on the R value, depth of padding (a better night’s sleep means a better chance of continued silliness the next day) and the fact the GoLite quilt has no back section in the bag. So bag choice is determining pad choice.
The Balloon bed is good, it works, pure function, but the balloon bed with a OMM Duo Pad for the legs is about the same weight as the PAC mat, with a much greater R rating.