Then you'd upset the Strauss fans
Would "changing the soundtrack", if at all feasible, affect rolling stock performance?
The Desiro sound, I don't mind it. One can barely hear it from inside as the carriages are well-insulated, and I've always thought them quieter than the Electrostar equivalent. The earlier CAF/Siemens 332/333 builds have a smoother Electrostar-esque sound, quite a different design, but Siemens lists them as a Desiro product on their Mobility website.
My ultimate favourite has to be the 365/Networker sound. And not just because I've grown up with it, it is
the original AC sound! All else I have to say as a conclusion to this great traction sound debate is, each to their own!