Personally I prefer a bit of variety when it comes to the sounds on offer. I have a number of Class 37's and have at least one fitted with Sound from the main suppliers: Digitrains Active Drive, Legomanbiffo Drivelock, Howes, SWD and Olivia's. Each have their own merits and I still enjoy the range of different sounds you get and the different driving techniques
required. Yes, the sounds and speakers have improved, but unless you're a connoisseur there's no need to start replacing or upgrading your whole fleet. One of my favorites is still a Loksound 3.5 with SWD sound. Kevin.