I'm such a guy (but I also got multiway speakers) and not that old (43) and with good ears. Single driver speakers have something special no multiway speakers can do. And modern hi-engineered drivers like those from Mark Audio are way better than this driver in this GR speaker. They have a very flat thin cone and a kind of phase plug that makes their dispertion a lot better. And with the spider and surround they have 8mm xmax or so, so they can play bass better than most small midwoofers.
The GR driver is too small to be used as single driver speaker, it needs a sub. And it's bad engineered (sadly there are many such arround) so the tope is terrible. Even i as fullrange single driver speaker find this terrible. I use 5" or bigger drivers for my own builds like this bookshelf that i use in my office. Driver is the Mark Audio Alpair 10.3M in a 17.9L reflex and with a correction filter to tame the top end. And these sound good for this kind of setup. This is how i use them, in my office and driven by a Marantz PM5004 amplifier. They are against the wall, but were designed with that in mind. The finish is intented rough. I'm not so fond of how speakers look today, so i did not do the shiny polished look... I have no ready to publish measurements, and no rig like Amir to test them, but i love how they sound.
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A multiway will always have a better dispertion and a flatter response, that is true. But not the true source point sound and lack of phase shifts that most, if not all multiway speakers suffer from. So it's a matter of choices of compromises. This speaker is not everybody's cup of tea.
But again, this GR speaker is just crap, even for a single driver setup. And those prices are totally crazy.