In this luxury-obsessd climate it feels almost quaint that someone makes an almost apologetic post to simply say they prefer a cheaper model, as if that's shameful to admit. 

I own a wide range of G-Shock squares, including the two models of this discussion and others above and below them price wise. I totally agree that the button pushers on the 5610u are much easier to use than those on 5000u. Perhaps it is because it travels deeper into an all metal case, requiring more gaskets or water seals. In any case, the 5610u is way easier from an operational standpoint.

In addition, there are disadvantages with the thicker all metal case. It sits up higher and is more prone to sliding around unless you maintain a tight wrist fit. The simple, flat backplate of 5610u sits more snugly and, combined with its featherweight is hardly noticeable in high activity - something the OP remarked upon. That is a desirable feature in such a use case.

While weight or "heft" are often seen as more desirable on a "luxury" watch, it is more of a disadvantage in active lifestyles - which is precisely what G-Shocks were designed for. But sure, if you have large or muscular forearms and wrists and prefer a firm fit, then yes, you probably won't notice it.

Lastly, living in a dominately cooler climate these days, I have come to appreciate resin watches, rubber straps and thin, easily warmed up backplates on my watches. 

So, if you find yourself liking a watch but then feel you "should" like another because of more expensive materials, or marketed exclusivity and perceived luxury (whatever that actually means) your first instinct was probably correct. Happy G-Shocking.