Some care should always be taken when replacing the component manufacturer's stock supplied feet.
IME, while many manufacturers don't always select their chosen feet very carefully for maximum isolation benefits ,they nonetheless voice those components using them and thus swapping footers can easily undermine musical properties that the manufacturer designed into the product.
Regardless, often aftermarket footers can be very effective tools for fine tuning for component,system and individual requirements.
I find that most elastomer devices have a negative impact on pace,dynamics and timing.In addition, the benefits of using elastomerics is very component specific. To my ears, the detriments more often than not, outweigh their usefullness.On the occassions that a damping device is required or beneficial,my experience has been that the most consistantly effective of these have been the EAR footers.
I consider most cone devices to be mechanical filters that produce specific tonal emphasis or sonic effects.The shape of a cone is one of the major determinants of the narrowness of the bandwidths that are enhanced.Straight sided and steep cones will have the most narrow frequency related characteristics.Non-linear,curved sided cones tend to have a broader,more even balance.
Of all the cone type devices I have experience with, the most widely effective,PRaT friendly, broadband cone footer has been the "Jumbo" cones from DH Labs.I recommend them highly.