"What are the pros and cons of using spikes compared to VT Feet?"

Both options will have a significant influence on your system. Remember that the aim for such products
is to reduce vibration transference in order to produce a purer sound with less added artefacts i.e. a 
neutral reproduction of the recording without the hi-fi system adding its own coloration. An additional 
bonus of achieving this will be a reduction in the antisocial problem of noise transmission via the building’s 
structure to adjoining rooms and neighbours.

   An ideal situation, though not possible, would be to have a free floating unattached speaker.

The approach of trying to couple the loudspeaker base to the surface has major inherent problems which
include the difficulty of trying to make a perfect union between the cabinet base and contact surface 
- the tiniest imperfection here will lead to resonance. Therefore, there is a need to minimise contact 
between the speaker cabinet and any surface it makes contact with, in order to avoid resonance and 
loudspeaker cabinet motion. Advocates of spikes believe that transferring the weight of the speaker on
to focal points i.e. an enormous weight per sq.cm, improves contact between the speaker and the surface
it is in contact with. This results in less movement and vibration plus an 
improvement in sound stage, 
clearer middle and control of low frequency noise.    

VT Feet address the situation by acting as a decoupling isolator, utilising state of the art high tech 
engineered materials with unrivalled vibration absorption  properties.