I use the lightest weight Paramo. The big thing in terms of temperature control is that they vent really well. The Velez Adventure Light Smock, for instance, has a zip from neck to bottom of chest, one either side from armpit to hip, and the sleeves easily pull up above the elbow. The trousers unzip up most of the leg. If it's still too warm for me to cope like that, then I probably wouldn't feel the need for a waterproof (or I'd be using my 2.5 layer running shirt).
With Paramo, you have to have a different mindset to Goretex. Buffalo is similar but aimed at colder weather.
It isn't bombproof. Heavy rain in a strong wind will eventually get through to your skin. But then your body heat pumps it back out again. And you stay warm even when wet.
It isn't part of a traditional layering system. Ideally you'd wear it against your skin, or with a Paramo baselayer, and not take it off all day. Extra warmth is added by overlayering.
It's the pump that gives it an edge of Goretex. With a hardshell, any moisture inside stays inside (breathability doesn't make a difference when liquid water coats the inside). That moisture could be sweat, rain that got in up cuffs or down collar, river that came up your legs during a crossing, failed membrane on GTX. It also means that it can take a lot of abuse. Mine has stitched up repairs and sewn-on bedges that make no difference to its effectiveness because it doesn't rely on an unpunctured membrane.
