The original RNC was the first compressor I bought. Now I also have two of the 500 series version. The main benefit over the original one is that the 500 series version has balanced inputs and outputs. When I record vocals, I always have the RNC 500 compressing the vocals in “Super Nice Mode” on the way in. In the past I’ve used the dbx 160A, the dbx 266xl, and the Warm Audio WA76. While I was able to get usable results with all of those, I feel much more comfortable getting the sound I want from the RNC 500. It’s less muffled and distorted than the WA76, and able to be more transparent than the dbx options. I plan to keep these in my rack for as long as I’m recording music.