Certain designs of replacement footers offer an immediate and noticeable impact on the presentation when used on a device, especially a source that is mounted in way that lets the local environment have an impact and effect the performance.
Certain footer designs will reduce the environmental impact and produce a sound quality with a noticeable change and usually one that is seen as improved.
If a system in mounted (especially the source) is being used in a way that has already used measures to isolate the local environment effects, there will be very little extra performance on offer when an exchange footer is used.
There will be a change, but whether it is used for the overall better will be unique to each location.
In my system with footer exchanges, I do not detect any improvements in fine detail retrieval when exchanging a footer.
I can change the speed of the Bass Notes decay and tweak the Upper Mid's projection.
Either or these are not improvements, just a presentation tweak.
In my experience of exchanging footers in my system and other owned systems, the most noticeable impact on a Sound Quality and Presentation has been when the exchanges are on a Idler Drive Turntable.