I know that a F plug is considered hot because a four-stroke plug has to be hot because it ignites every second stroke but I have my doubts about the theory when it is used in a two-stroke.
Not hotter, just better heat retainage, that is they keep more of their heat through the exhaust and intake stroke. Some brands of four stroke plugs are actually fairly cold. The K&B 4C for example will seem to be a very bad plug unless you are using 20% or higher nitro. But unlike a cold two stroke plug it will maintain a low and smooth idle. If you fly C/L with a four stroke and venturi, no throttle; you will not even need a four stroke plug.