I have had a set of Lamkin's REL 3Gen midsized grips on my irons for about 6 months now and can't recommend them enough. They have been in my car through the summer in the southern heat and show no signs of drying out.
I have tried Golf Pride dual compound grips and while the cord part holds up i noticed that too many of them were shot after a few months of heat. They would get that dry shinny feel to them.
Tried Winn grips too but to be fair i think it was a bad selection of grip type. Tried one of those spongy types for added grip in the rain. Didn't work.
These 3Gen's are great. They actually do get tacky when its humid out. And hold up well though heat and cold. Don't think I will be replacing these for a while. And at about 5 bucks a piece its not very expensive replacing them on a whole set of clubs.
I would recommend these to anyone when the golf season gets fired up.