I don't know, the 3MM Farmer John is very versatile. For kayak fishing, I'll wear it alone in the summer, and combine it with a Mysterioso base layer on cold days. Works great - I have the NRS one and love it.
The type of suit you're wearing makes a big difference too. Certain 3mm suits will feel like a 5 depending on how well they fit and if they're smooth skin or lined.
My 5mm Henderson lined full suit lets water in along the zipper and not having any smooth skin neoprene water clearly moves in along my legs and arms. Not a lot since the suit fits me well, but when you wear a tighter suit or one that's smooth skin on the inside you can tell the difference.
My new 5mm 2 piece (no zippers) Sporasub is clearly warmer then my old 5mm Henderson. Closer fit and a section of smooth skin around the wrists and ankles discourages water exchange while swimming. The water between my skin and the suit just cooks since it stays put. In the Henderson there's obviously more water flowing through.
Hybrid Mode
