Fiberglass has a higher R value so its probably beter between you and the water! But on a day were its below freezing, the water is still above freezing and frost will collect on both! The floor in a glass boat is one layer. My Willie has a floorboard setup in it so its warmer on the feet on a cold ass day or any day for that matter! I would amagine though that the metal boat would hold colder temps and radiate them more meaning it would be colder in general. I havent ever noticed it though as I row all the time, have 5 mill neos for winter and 2 heaters in the boat. If your dressed to fish 28 degree weather, your set for 25 probably also. I think sleds are just more boring to fish out of so you get cold! (this is my opinion)...however there a blast to drive! Id never fish though cause I be terror on the water! Its a good thing I dont own one (yet) and go on the nootch. There a absolute hoot!!!

Bob D