Wouldn't "stiffer" mounts result in a noisier machine?
Not necessarily. As you can imagine, these mounts degrade with time and, after 6-7 years, it would be a smart move to replace them . . . certainly if you ever replace the pump. However, it does appear from your pic that you have these better mounts.
The mounts originally fitted to my Anita (12/05) were likely sourced by Quickmill and had the Ulka name embossed on them. They were very soft compared to the ones now sold by Chris' Coffee.