Do most riders have different sets for different seasons, they are expensive, so is there a middle ground?
That's part of the point with these things. You wear the same thing weather it's 119 degrees in Phoenix (dang glad to be wearing them in the 2009 Iron Butt Rally) wicking away sweat and helping in cooling and in addition to my electrics in 40-something Minnesota (yep...same rally) as a base layer for warmth. Or, I wear them with electrics and a fleece in the teens.
The middle ground is they work in a 72-degree dawn in Kentucky (yep...same rally) just as well. Wore that same set of LD Comfort for 11 days straight (I did soap up in the shower with them on in Bemidje though).
I have two sets of the same stuff if I'm on a long ride these days, but still do wear the original set of the long-johns and full sleeve as part of my rotation.
I've found for adventure riding they're even better than LD riding.
They are expensive, but worth it.