Hi all,
I run hot also and find wool sweaters/socks/hats/etc. to be my best bet. Wool wicks and seems to insulate me just as much as I need. Thick cotton layers overheat me and keep the sweat close to my skin and I try to avoid synthetics as much as I can. All that said, my one use of those two fabrics is my outer layer: a 1970's Sears mechanics jacket with a cotton/poly shell and a cotton flannel lining.
Best,
e.