You are gonna love how completely the Auralex Gramma/Subdude isolation platforms eliminate your suspended hardwood floor’s propensity to drone along with the subs. I used the Auralex Great Gramma (bigger version of Subdude) to great effect beneath the quad of Paradigm Servo 15s I once owned.
On to your direct question- If the spikes are already threaded in place of the stock feet, I’d just leave 'em on so the sub securely couples to the platform.