First off, I have no experience with Klim or heated gear, though one day maybe.
I've ridden in low-mid 20's for 3 hours, before it got up to 32 degrees, and I was warm, at least my core and legs. I started with a tight base layer, you know, the synthetic stuff, and over that I used a cotton mid-layer (long sleeve). I have what would be called 4 season jacket and pants (Clover), but really it's only 3 season (Fall, Winter,& Spring). They have the thermal and rain liners, and I put both in, as the rain liner really holds in heat. I didn't feel cold at all with this setup. I wore 1 pair of socks, and only felt the cold at the tips of my toes, but not freezing. A balaclava helped under the helmet, but due to fogging, I had to keep the shield cracked open. Hands is where I really felt bone chill. I had forgot to bring winter gloves, probably because I don't like wearing them, and my Scorpion SGS gloves have tiny holes in them for ventilation. In the Flatistan Summers, those holes don't appear to do a damn thing, but in the 20-30's they become quite obvious 🌬. Having grip warmers does nothing for the outside of your hand, so maybe hand guards would have helped. I think, other than my hands, that I did really well.
Also, I don't think there really is a 4 season setup, at least not that I've seen yet. Maybe in the far northern areas, but not in most of the states, and especially in the South. My aforementioned gear will get me to about 85 degrees, but from there upward I have to put on mesh. Mid 90's and high humidity can be brutal. So mesh helps in not having a heatstroke.
My northern comrades probably have the best advice, as they deal with the cold more regularly.
All the best,
Rob