My folks used Open Pit with a little melted butter too. It was delicious on grilled chicken. While I usually make my own sauces, occassionally I will use a commercial brand and "doctor" it up a bit. I bought a bottle of the original recipe O.P. today. I think it's different from other brands because it is tangy and staight forward red sauce. Sometimes I like a break from sweet, smokey (artifical), and sticky sweet.
I like to mix it with about 6 oz. of beer and 1 pkg of taco seasoning. Everyone that's had my que with this simple sauce has loved it.