I have the Mishimoto weighted knob. I've also run an old aluminum heavy shift knob. The heat in the summer is a decent trade off, I keep a sock on it if it's going to sit in direct sunlight and take it off when I'm ready to roll. Well worth it, really. Or just deal with the heat, it's not that bad and cools off quick once your hand soaks up some of the heat it stored
You can also look into the Carbing high grip shift knob. Same style, but if you get it in black the material is delrin, which does not conduct heat from direct sunlight and store it.