Isoacoustics' Gaia eliminated a 120Hz mode

The manufacture recommends going bigger as well. This supports the notion that there is a range of effectiveness and that minor adjustments may yield a questionable return. Perhaps someone can tune it but I have neither the patience nor the butt to do that. 
I do agree that each corner should have the same give or wobble when pushed, indicating each is pulling (supporting) its share of the weight. I did have to do some adjustments on one of the mains as it was apparent that one corner was clearly shorter than the others with initial give before resistance. I think relatively level, symmetric movement fore and aft and logos facing front/rear is what I am going for.

Another point is the Gaias have rated capacities to cater for different loadings. This just shows the importance of loading them correctly. They will fall out of the performance envelope if not properly loaded. I presume it is better to have a higher rated capacity Gaia support a lighter load rather than the other way round.

I read somewhere that with a correctly set up Gaia (logo facing the front or rear), the speakers can sway slightly from side to side but stay firm on the other axis without any movement at all. As for leveling, agreed that it doesn’t make much sense since speakers are heavier at the front due to mounted drivers. The other points you brought up are valid.

Nevertheless, I presume that the Gaias need to be loaded evenly for them to work properly. The loads from the speaker need to distribute evenly to all 4 supporting Gaias. Otherwise it will just defeat the purpose. An exaggeration to illustrate my point, imagine one end of the speaker at the base is hanging loose in the air while the other 3 footers are taking most of the load. The sound will not be good. This is the reason I messed up during the first time I installed the Gaias.

It is easier to set up the Gaias if your floor is completely leveled. In my case, the floor is slightly uneven so I will need to adjust the leveling to ensure that all 4 footers are evenly loaded if not perfectly loaded. I understand that perfect accuracy is not possible due to the aforementioned reasons. Nonetheless we can still set up the Gaias to achieve the best possible result with some effort. My speakers are sloped at the top so I can’t control the level at the top of the speaker. The control was at the top of speaker stand in my case with the use of a spirit level.

I do not understand the rationale for leveling nor the logo directionality. Speakers are typically heavier in the front so compressive forces are going to be different, which I would think affects function. Also, some speakers need to be canted forward or backward to align the tweeters with the ears which obviates leveling. I also noticed that depending on how the drivers are mounted, the cabinet wobbles more in one direction or the other, with the more wobbly direction being along the narrower axis. If you turn the footers 90°, the wobbling remains the same.

I am not denying that perhaps totally level and logo straightahead don’t make a positive difference, I just cannot explain how they would. 

Give it few days to settle down. In my experience the bass and everything showed more presence and impact after few days of settling down. Basically a more fleshed out and open sound with improved clarity and macrodynamics.

I am not sure if this is worth mentioning. Personally I find the installation of Gaias to be rather finicky as a perfect accuracy in the leveling cannot be achieved. The individual Gaia units have to be rotated clockwise or anticlockwise with the logo facing the front or rear. If the floor is not a perfect level, you would need to adjust the 4 Gaias so as the speaker will be completely leveled with proper even loading to all the Gaia footers. This adjustment may cause the logo on few footers to face the rear instead of front.

In my limited experience, an improper setup of the Gaias will result in a poor sound from the system due to the uneven loading. I messed up the first time when I installed the Gaias on my speakers. After some adjustments to the leveling, the benefits are difficult to ignore.

I realized I was going to have to do some significant modification on the Nobsounds, including drilling out M6 size holes so I could screw them on to the DBA subwoofer cabinets. I was also going to heat shrink them for stability. I did attach one set, albeit without the heat shrink, and while they did bounce, I wasn’t sure about the aesthetics. So instead I installed Gaia IIIs. I also liked the idea of consistent technology all around. 
The bass is smoother but also seems to have lost some of the slam or impact it had. After a while,  I realized I was still “hearing” the low notes but that the impact had decreased because there wasn’t as much direct transmission through the floor. The structural resonance has also diminished. It’s a new listening experience and one that will take some getting used to but overall is likely more authentic. There is less physical impact, which was probably of an artificial nature, but also fewer cringe moments when a nasty room mode hits. And I still feel the low organ rumble and the thrum of the bass notes, just not as much and not as often but still as deeply. Overall, I don’t miss it. I think it’s similar to when you’re installing a subwoofer and you initially like it turned up  but over time you realize that a lower contribution is better. 
In a more general sense, I will say that the entire presentation seems more defined, the instruments and voices start and stop more precisely, and the overall sound more articulate and three dimensional and less “attention-grabbing”. Its an easier listen. 

I use a pair of Gaia II with Marten Duke 2. The Gaias are very effective as they improved everything across the frequency spectrum. The largest improvement was with the bass but the midrange and treble also gained some clarity and sophistication.

The bonus is they look rather good when installed on the speakers. The speakers now look more elegant with the Gaias than with standard spikes.

I use the GAIA II under my GE speakers and the sound definitely went up a few notches.  It’s one of the few tweaks I tried that truly works and can be heard within the first few minutes of listening.