So which ones do you prefer?
All my heads have the silicone and the one gripe I have about them is they squish too easily and also get sliced somehow, causing shorts.
But I wonder if the rubber ones may be much harder to deal with?
Conflicted!
In my experience the rubber ones tend to become hard and brittle after a while. I prefer the silicone. They do burn and split eventually but they last longer than the rubber.
Someone gave me an old Pro tank recently for some reason, it came with 10 used heads. I was going to rewick them but they were different to the ones I was used to. The slots at the side were too narrow for the drill bit I used for PT coils, and they didn't go down far enough. Don't know if they were a new design, maybe done that way to stop people rebuilding them.