When the game 'IAGO Chess' (contrast with The IAGO Chess System, which is a way to systematize all of chess, and has the game IAGO Chess in it), it was meant to address issues I saw with Seirawan Chess:
1. The 9 queen problem.  It is theoretically possible to have 9 queens in chess, but they don't supply 9 queens.  This may seem ok to people, if the idea of flipping a rook (not in the rules) is used to signify a queen.  The 9 queen problem becomes worse, when you try to add even a wider range of pieces.  Exactly how does a physical version of the game handle this?  As I see it, it is not able to.  This hinders the adoption of chess variants, and chess continuing to evolve.

What IAGO Chess states is that you are limited to your piece mix.  Due to the sheer firepower added (3 queen level pieces) available.  It also addresses the issue.

2. I have issues with the case of where you may not be able to get pieces onto the board from reserve, if you just only allow for gating as a way to get them onto the board.  All reserve pieces should have a chance to get onto the board at some point.  Not allowing this means that reserve pieces are merely an extension of the opening game.  This hinders the depth of the game.

3. If one is going to work on 'The Next Chess' (Seirawan would fit into this), as opposed to a gimmick (or unplayed variant), it should represent the fullness of the chess experience.  Things should lend towards maximization of options, so that continued play can show what should or should not work.  From EXPERIENCE of play, of MULTIPLE people, consensus should be reached.  For this reason, IAGO Chess (in the IAGO Chess System) is set up how it is.  It is meant to be played and seen from multiple eyeballs.  The IAGO Chess System framework allows people to adjust their own game, and take out what they want or don't want.  The idea is to get enough games close enough playing, so we can see what will work.  This is critically important.

My take on what happens is people have pet projects they label a 'Chess' as if it is supposed to be a full-blown game, one that joins a flood of other games, and it is a discrete item that doesn't lend to the body of language at all.  What should be derived is what people collective decide to play, that can collectively lend to the experience.
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In all this, I do have much respect for the pieces and suggestions you have.  Even your recommended form of displacement in Alternative Chess, I believe is something that should be played.  However, I think what you have in Alternative Chess, is merely a rules tweak that can be applied when there are reserve pieces in play.  Labeled as a full-blown game, it gets boxed in and not played.  Same goes with your 'Reformed Chess', which I see as a mutator for chess, rather than a full-blown game.  Same with all your neat pieces.  These pieces should be put in Alternative, IAGO or Seirawan, or some other form that uses part or all.

What is needed is a community to play with a range of mix of rules and pieces, and a framework to manage this.  Arguing over Seirawan, IAGO or Alternative ends up not advancing anything.  PLAY should dictate this, as the use of your 'Reformed Chess' pawn.

If this is not done, we aren't going to have 'The Next Chess' (the proper adaptation of chess which reduces the number of draws and makes the opening less stale).  We will have a variant community that is continued to be divorced from the normal chess community.

And, as far as 'IAGO Chess' goes, I suggest the IAGO Chess System be looked at, and what is in it, as far as specific game rules, be proposed and adopted.  IAGO Chess (the game) can be modified as play and experience dictates.  Let that be what the community deems to be 'The Next Chess'.

To sum up, we need a whole lot more PLAYING and less PROPOSING of ideas, and adoption, and community that will play these.