How important are spikes?

On hard surfaces, rubber footings, like IsoAcoustics, are your best option.  On carpet, you want to poke through it.

If the threads for spikes are inside the speaker footprint, consider after-market outriggers to make them more stable.

He's talking about spiking a rack, not speakers.

Any which way, if the carpet is over a suspended floor, you want to decouple.

Wheels are a big mistake. Even simple brass cones would be a big improvement.