Go with the spikes. Never could figure whether spikes "coupled" or "decoupled" the speaker from the cabinet but every speaker I've added spikes to sounded so much clearer, more detailed and transparent whereas rubber feet don't do much at all. You will not be sorry going with spikes. You can purchase some do-it-yourself spike kits on line from Parts Express - they carry good, yet inexpensive spike kits from Dayton Audio which even include metal disks for under the spikes to protect your wood shelves. I used the 1" spikes under my VonShcweikert VR1s and they made a great speaker truly outstanding.
Good luck.
Good luck.