Actually, I've met a lot of people who feel this way. "It feels nice, but the keys are too tall." "I can see why you like it, but I have to push so much farther."
I explain to them that they only have to depress the key about halfway, rather than all the way to the backplate, so it's actually about the same, and while a few have tried this, and had it work for them, most have felt it was much too difficult, especially with a topre.
You could also try a dampened ALPS board like the AEKII, or a Dell AT101W that had the sliders transplanted from the aforementioned AEKII.
Another think you could try is the low profile topre keyboards, or one of the silent models. However, I believe only the JIS layout is available on either of those.
But yeah, while the majority of the keys on a realforce or hhkb are pretty damn quiet, the space bar is quite loud for most people, and they just can't compare to the quietness of most laptop and low profile membrane keyboards in terms of sheer silence.