Footers under my speakers double the perceived value of my speakers!

I thought boats floated. 

I thought boats floated.

Boats float. You need to learn some simple grammar. 
Turds float too. That should be close to home for you. 
And then there is the famous Monty Python skit from Holy Grail. 
But if you are referring to my reference to "free-floating in space" descriptor, I don't regret my choice of words. Read in context, which is likely beyond your skill set, I think my choice of words is appropriate to convey what I heard. 

@audiopoint - I don't want to leak information from my former employer that isn't already well known or certainly available from other vendors quite well known and represented here in the forum, or available on his website.

In response to your use of "brass and copper alloys at a 5/16” thickness".
Copper for example has a Young's Modulus that simply is superb for baffle material on the tweeter drivers them self. If I were in a position to manufacture high end audio, I would certainly be using copper baskets to attenuate ringing of the speaker basket. Brass is one of I think about 400 copper alloys? I would certainly search for an alloy of copper if you were to continue or rather resume research.

So I might as well name drop so we know where I am getting my information from. I used to work for Mike Lenehan in Australia, so the devices he uses are specific to his loudspeakers. Essentially his loudspeaker designs use spring steel plates laminated to the top, side walls and baffle of all of his later designed speakers, these were connected electrically like a ground plane, not unlike a Faraday Cage, whilst simultaneously creating a more rigid enclosure.

Cross bracing he uses I cannot divulge too much, however as he has it listed on his website and other places, I can tell you that he does use silicone filled rigid copper tube as well as cast iron rod as cross braces. Interesting that you also researched similar materials
**I think if you want to know more regarding this, you might want to contact Mike Lenehan of Lenehan Audio directly**
Mike does get a significant tax break for the research he does, and has to report to the Australian Government each tax year.

Making a more rigid enclosure doesn't entirely remove resonant frequencies of the cabinet, it simply moves them to different frequencies, as I suspect you well and truly understand from your comments. Mike used the sacrificial method of leaving the back and bottom of his loudspeakers without the extra rigidity of the sprung steel plates. This is to release the energy in a manner that least affects the sound field being voiced by the speakers.
However in moving the resonant frequencies towards either less important bandwidths or preferably outside audible spectrum of frequencies, you are simply modifying the energy, channeling it where it can do least harm.

With the acknowledgement that the cabinets are specifically designed to integrate well in an isolation system that attenuates energy from under the loudspeaker; you understand that in Lenehan Audio's design it is no accident that it works exceedingly well. However in not so inert cabinets, the effects of isolation may have even a greater effect on improving the sound.

Since then, I have tested spring isolation on other loudspeakers, even one in a hifi store in El Paso, where I placed springs under the amplifier, and source electronics. I then placed it under the best floor standers he had in the store. After listening he excused himself and introduced two of his techs to hear what $20 worth of Smalley's wave springs from Ebay just did to the sound. That's when the questions really started coming - after you hear it, and there's no mistaking the improvement.

USE SPRINGS WITH CAUTION
When you truly float your speakers on isolation, you should be able to move them (regardless of weight) with your pinky finger. If they are rigidly mounted they are NOT nearly as isolated as they aught to be for maximum isolation, and sonic improvement.

Speakers, especially floor standers will become compliant to forces in all three axis, which means the center of gravity can be easily moved across and over the base. Townshend Audio use outriggers, to broaden the base to account for this. I highly recommend anyone placing springs under their speakers to broaden the base of the speakers!!!

Whatever approach you use, or product, if your speakers are not compliant with a tiny amount of gentle force - they are not zero stiffness.
For better results than I am putting forth with tuned spring isolation, please research quasi zero stiffness.

If any of you are interested? on my system page, the easiest way to see speakers on wave springs, the copper colored pair are sitting on Smalley wave springs. You will see the gap and shadow under them above the heavy stands.

The first image you can see a shadowline under my sub, it is on compression springs, as is my amplifier and source.

https://systems.audiogon.com/systems/8721

@fsonicsmith
the Gaias I suspect are more rigid than springs in a zero stiffness tuned loaded spring rate for >10Hz isolation?

I for example would NEVER place 4 correctly loaded springs under your Devore O/93 where the spikes would be placed.

WHY NOT?
Because broad frequency isolation requires compliance in the device suspending your speakers. The center of gravity with little force could easily move towards the limits of your base on those speakers, making them liable to topple over if you bumped them.

The very fact that the IsoAcoustics can safely hold your speaker up without compromising the safety of them is an indication they are not compliant enough to fully isolate them.

Both the frequency and amplitude of the frequency needs to be accounted for in isolation.

I don’t know what vehicle you drive, however I’d bet you can grab a wheel arch and without too much effort lift it a quarter inch by one arm??
Consider how much your vehicle weighs and how compliant the suspension is, even with that immense load.

It is the compliance to even small energies in higher frequency, and larger amplitude at low frequency and up that make for good speaker isolation.

I would broaden the base upon which the springs are set to move the edge away from the center of gravity - just like Townshend Audio does.