It went more quickly with Alfaerie, because it's easier to spot differences in color than differences in orientation. However, while doing it with Alfaerie, I was not taking any time to get any sense of the position, yet I would certainly have to do that if I were playing Shogi. Also, Shogi does not progress from one random position to another. The position changes incrementally, starting from a position where I already know where everything is without even looking at it. So, I would be able to use my knowledge of previous positions to understand what the slightly new position is.

Yeah, sure. Who needs the reminder of pieces? You might as well play blindfold... Well, for GM players that is actually true.  When they think far ahead they intentionally don't look at the board, because it just distracts them with the current position. But for mortals like us playing blindfold is a huge handicap. The sole purpose of having a board and pieces is to constantly remind us of what stands where. And the test shows that Alfaerie des a better job at that.

Recognizing the piece type is of course at least as important as recognizing the color. (Some servers offer an interesting 'semi-blindfold' mode, where you can see the side pieces are on, but not their type, like playing with blank tiles or checkers.) This was never contested. Coloring the pieces does not have any effect on the ability to recognize the type symbol, though. (I hope we agree on that, rather than having to prove it with a 'Spot the Queen' applet...) So it isn't really relevant that you also have to recognize the type; there is no need to degrade the side recognition for improving the type recognition. (And it will probably also not be contested by anyone here that for westerners kanji are doing a poorer job at that than pictograms, as far as type recognitiion is concerned.)

From whatching Chu-Shogi games by experience Chu-Shogi players, I noticed that these frequently blunder in an elementary way (such as overlooking a discovered attack on a high-value piece), and that I, as a non-player, could almost always predict when they were going to blunder. Because I was viewing the game with mnemonic pieces on my bot, while they were using the standard kanji pieces of the client. So it was obvious to me they suffered a iszable handicap by not seeing the board and pieces as I did it. It will of course make a great deal of difference how much time you have available. In correspondence play, where you think perhaps an hour per move, chances are good that after some time it will start to dawn on you that you misidentified a particular piece, and when you do you have every opportunity to think again. In real-time games you often will move before realizing your mistake.

As to the auhenticity... Seems to me you pretty much threw that out of the window when you abandoned the kanji. No Japanese would ever agree that there is any authenticity in these pieces. In fact I noticed they tend to even deny that you are playing Shogi, when you use non-kanji pieces.