I run ProAc D15's and use Herbie's Gliders with the stock spikes. Happy as hell - they slide with ease on the hardwood floor. Soundwise - a little tighter bass but you have to adjust the spikes to keep them rock solid to the floor. No movement at all. They go out of adjustment every month or so.
Is Spiking Necesarry?
I like to move my speakers around a bit for to test how they sound, so I slide them. I have the Proac D48Rs, they are kind of heavy so with the spikes in it makes it tough to move them. I haven't consciously tested or compared the sound with spikes or without them. Does it make a difference?