On some single cams a stabilzer is quite beneficial. Quite a few have a significant kick on the shot, coming from the cam. A stabilizer can really dampen this. There is also quite a bit of vibration reduction and most will reduce torque, though probably not a lot.

When it comes to adding Sims products like string leeches, cable dampeners and limb savers, there is no down side that I can see. They will reduce noise and vibration in virtually every instance, which can make a shot feel much better and sound much quieter. The fact that they are not expensive makes them a good investment in my view. I've even heard that they can extend limb and riser life, when removing vibration. I don't know if that has been proven, but it sounds reasonable to me.