I went down almost 1/3....but that was in conjunction with getting married. My wife had manufacturers so I jumped in and then joined and got commercial auto. I was with State Farm and THEY are the ones that told me that i would be better off with Manufacturers (better coverage at better prices).. They also do not surcharge for occasional tickets or minor accidents---but they will drop you if it gets out of hand. Also--you get a dividend check at the end of the year (usually a couple hundre on the 3 autos I have on it). Once you are a member and get the insurance, it also helps your employees get the insurance which is a good perk.
You can email me if you need more info Ocutter.