Bought one for my wife for Christmas to replace her defective BA Insulated Air Core pad. Both weigh 24 ounces; the Thermarest is 1-1/2 inches thick vs. 2-1/2 inches for the BA.
Inflation: The Proilite and Prolite Plus pads still claim to be self-inflating but they are NOT. Open the air valve and they sit there, flat as a board. Even after lying there overnight, it did not inflate. Had to blow it up by mouth, like the BA. Noticed the same thing with my (man's) Prolite Plus. I'm told last years Prolite 3 and 4 models were the same way.
Comfort: fully inflated, I can lie on the P+ on my side on a concrete floor and not feel the floor. The 1-1/2 inch thickness works, and I roll around a LOT.
Got rid of my OLD Thermarest pads a decade ago in an effort to save weight. I've since learned that a good night's sleep along the trail, especially on a multi-week trip, is worth its weight in sleeping pad. SUL be damned; I'm budgeting 24 oz no matter what model or combination I use.
I got a (mans') P+ for me too. The man's Regular also weighs 24 ounces and is the same 1-1/2 inches thick. but is 6 inches longer. The trick to keeping the weights the same appears to me to be in the amount of foam core removed and the pad length. The woman's model appears to have removed less foam (less coring), hence its higher R value (4.6 vs. 3.8) for the same weight, achieved by simply making the pad shorter (66 vs. 72 inches).
The mind begs the question "what data does Cascade Designs have that suggests that women with a body length greater than 66 inches sleep significantly warmer than those of 66 inches or less body length?". My experience counteracts that; there are a LOT of women in this world taller than 66 inches and some of them are backpackers and trekkers. Corallary: "And what makes them think us men with a body length greater than 66 inches - and therefore forced to use the longer, lower-R pad - don't get cold at night? Don't we deserve equal treatment in terms of R values? Sounds like Marketing BS to me, all is the name of hitting a given weight point.
I submit this constitutes sexist stereotyping at its worst and that BPL should lead the charge with a class action suit in behalf of backpackers world-wide, be they male, female, hemapthrodite, or trans-sexual.
It's time for my meds now......