i use both softshells and windshirts ...
my rule is that if its highly abrasive, ill use a softshell, if not then a winshirt
things to note about softshells
- some WEAVE non membrane softshells can breath better than some windshirts, it all depends on the fabrics ... also weave softshells are often not fully "windproof", they tend to let a small amount of wind in which helps with breathability, but may well a bit "chilly" to some
- softshells are heavier ... period
- softshells are more durable ... period
- a softshell WILL absorb more sweat and moisture, and can become soaked ,,, ive had that happen ... windshirt can absorb moisture as well, but depending on conditions, you may just be able to take it off and shake it off quickly, it also dries quicker due to the thinner fabric
- softshells are "warmer" which can be a bad thing IMO .... if i want a bit "warmer" ill just wear my R1 copy under my windshirt or other such ... a shell should just be a shell IMO, no need for it to be "warm" ... thats what other things are for
- windshirts with pile interiors (buffalo, driclime, vapourise) are actually considered the first softshells ... the concept i believe came from studying arctic people where their version of a softshell was animal fur with fur on the inside .... these work quite well in lower temps but lose flexibility at higher temps due to their "all in one" nature
personally if i didnt need the durability of a softshell much of the time id use a highly breathable windshirt every time ....
for good reading go here ...