Isoacoustics Gaia II on what type of speaker platform?

Yes. I would think with carpet that a spiked footer would be the way to go. I have a pair if Magico A3. They come with stock spikes and pads or you can get Magico’s APods, which are also spiked. But I have hardwood floors and because of where my A3s are in the room, I was concerned about brushing up against a 100 lb speaker and inadvertently knocking a spike off its pad. So I looked for a different foot both for safety and acoustic purposes. I got the Isoacoustics Gaia I feet. I love them. Very stable and have a suction grip on the hardwood floors. Acoustically, good. How much better than stock points and pads. I am not sure. But what I am sure about is that for my purposes above, the Gaia I feet are a net positive. 

I too tried the Herbie's decoupling gliders, and preferred my previous spikes better.  The Herbie's softened the mid range and high end to an extent I didn't care for.  I now own the Isoacoustics Gaia I, and couldn't be more pleased - pricey, but well worth it.

I put my speakers on Gaia’s on top of thick maple cutting boards and felt that I got quite an improvement in resolution and imaging over the spikes that I used previously.  My listening room is in a basement with a fairly thick  area rug over a concrete slab. Speakers are AltaAudio Rhea’s. Never tried the carpet cups.

Nothing worked as well as the Herbie’s Audio Labs threaded Decoupling Gliders on the stand.

My experience, too. I recently installed Herbie’s giant threaded gliders under my four-post Sound Anchor stands for PMC IB2i, which are 95 lb monitors. I’m extremely happy with the results. My flooring is engineered hardwood glued to the slab. I previously spiked directly to the slab (before the hardwood was installed), then spiked into Herbie’s titanium glider cups. His glider cups were far and away better than any other cup I tried, including the ones from Sound Anchor. The big threaded gliders are better yet--and much better than the small threaded gliders, which I also tried, at least for my application.

By far the biggest insight: the height of the woofers from the floor has an astonishing impact on bass clarity, and hence everything up the chain through the mids and highs. I mean very, very small adjustments--a half-turn of each threaded footer, or less--altered the sound, once everything else was set in placement and the speakers were perfectly level. Get that woofer just a touch too low and the midbass thickens; get it just a touch too high and the bottom thins out. Surprised the s**t out of me! Woofer/floor interaction is little discussed but man, it’s important. The Herbie’s are threaded all the way to their low-profile base, so you can really dial in the height.

The IsoAcoustics were on my radar, and I even had the option to audition with return privileges, but they would have raised the woofer up too high, so I passed. No doubt they are excellent in the right situation, however.

I bought 2 cheap granite worktop savers and placed them under the Gaia.  This works brilliantly. It really transformed the sound, particularly tightening the bass.