I'm planning and have ordered all the supplies to do this silencing mod to my Realforce this weekend. From the video that guy posted I think this type of silencing is at least on par or actually even a little quieter than the official Topre silencing using the foam rings. Since the silicon sheet used for this silencing mod is so thin (0.020") it should have no discernible effect on key travel like dental bands or ironed foam pads.
If you check the link I provided in my last post, you can see that SpiceBar gets pretty much the same width for his ironed landing pads hence it doesn't impact the key travel nor the key feel.
The stem on the silenced Topres is longer than the regular Topre stem so even if the foam is ironed enough to be the same thickness as the Type-S foam disk, it will still impact key travel, however minutely. People using SpiceBar's mod have reported that the mod detracts from the Topre tactile feel, making it feel like a linear switch - some like this, others don't.
Never tried it and never will so I can't confirm but just a heads up because the stems are definitely different.
As he stated also, the reduction in switch tactility was due to the first version of the mod that he released. IIRC he didn't foam the landing pads. But I don't think that's the case anymore. He will give us more info about that if we ask him.
Even though you are right about the reduction in key travel, I don't think the reduction is noticeable. I may be wrong as I haven't given it a try yet.
Here you go: http://www.mechblog.org/
This is B7ad's blog on mechanical keyboards in which he details the silencing mods for Topre and explains the difference much better than I can.
I read it all. The fact is that he didn't try only the silencing mod but he did a lubing mod too. He also stated that the lub alone take away some of the tactility of the switch. I would then say that the silencing mod affects the key travel a bit but perhaps the tactility loss is only due to the lube. I would have to try it myself to be sure.
BTW is it possible to silence the MX Blue upstroke without impacting the clicky side? I guess that lubing a MX Blue would delete the whole tactility of the switch thus the board would be pointless afterwards.
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Lubing MX Blues doesn't "delete" the tactility unless you drown the whole thing in lube, in which case any switch would be ruined. People lube MX switches all the time including Blues. At most it would make the actuation smoother but it would still be tactile and it would still be clicky due to the clicking mechanism.

Lubing switches can increase tactility in a number of applications. For example lubing MX clears properly makes the bump more pronounced...
Further, I don't think you can't silence MX upstroke without shoving something inside of the switch to prevent the plastic slider from slamming into the plastic housing. As far as I know, no one has done this so far.
NGT have you tried Topre switches before?
The tactile spot of the Topre switch is pretty much at the top of the keypress, immediately after you start pressing the key. If you decrease the keypress distance at all, it will take away from the tactility of the keypress.