I've used ER some time ago. It seemed to quiet engine a little bit after first treatment.
However, I must warn you!!!
It uses chlorinated paraffin as a base. It it widely used in automotive industry (as antiwear & extreme pressure additive) as well as metal working production. If you take a look at shell motor oil data sheet it says that it uses very little chlorine. It's a carcinogen and considered one of the most deadly chemicals after some time contact with water and high temperature affect. If you get it on you skin, which I did about a dozen of times, it probably will get digested though the skin. It gets deposited in the fats and there is no way to get it our of your body. I stooped using it after I found this info on another site (unfortunately non-existent right now. I wish I saved the original article).
The same thing goes to Militec 1.
Their fuel system cleaner seems to work very well.