Alright, as requested. Apologies for the somewhat terrible and fuzzy photos. My workroom was darkish and I didn't feel like moving everything to get better lighting.
I purchased a 350mm Deep Dish Style PVC Plastic Racing Steering Wheel JDM Black/Red Stitch
and a 6-BOLT-HOLE STEERING WHEEL HUB ADAPTER KIT MAZDA MX5 NA NB
on eBay. Total for the wheel and hub was $54.97. The wheel and hub arrived in 2-3 days.
First, the wheel.
It's not terrible. The wheel appeared sturdy enough when I took it out of the box. The contact surface was very obviously synthetic, almost rubbery. You will not mistake it for fine Corinthian leather. However, it's actually not that offensive -- it has a pebbled surface, and has just enough give when you grip it. I don't know how it will hold up to hot Mississippi summers, but then, it's a $40 wheel. The horn button reads "T-Horn R" which is clearly nonsense, but marginally more acceptable to me than something like "Type R".
And now, the hub.
It's...well, it's a chunk of poorly cast metal with some poorly molded plastic bits on it. So, there's that. On the other hand, it's not required to do a terribly complicated or tricky job, so as long as the bits are mostly in the right place, it should work fine. The box was the most interesting part of the hub.
The English instructions, for example, were printed only mostly on the box.
But my spirits were buoyed by the optimistic slogan on the side of the box.
Installation of the hub was mostly straightforward, once I realized that I did not need one of the plastic bits that would have blocked the wires coming from the clockspring housing. The outer accordian-style plastic cover is a bit of a pain to refit over the hub if you happen to remove it (and I did).
Did I say mostly straightforward? Oh right. It would have been more straightforward had I paid attention to which set of screw holes I was supposed to be lining up.
Moments later, all is better.
Both the wheel and the hub came with horn buttons; the wheel with the aforementioned "T-Horn R" bit of nonsense and the hub with a plain silver button. Oddly...the plain silver button looked much worse to me. I don't like that the button says "T-Horn R" but frankly, any text or design at all is better than a plain silver button. I don't know why this is.
The horn button electrical spade-tab thing had to be pried out a bit so that the wire had enough room inside the hub. Easy peasy.
Tightening down the 6 screws is an exercise in frustration. If you overtighten one side even a smidgen compared to the other, it would jam up. For a while I was very careful and made only a few turns on each screw at a time. Then I got tired of that and started tightening down one side and then hitting the wheel with my hand to pop it free from the tension so I could continue tightening down the other side.
Finally, it was tightened down (or, at least, tightened down as much I could before the supplied Allen wrench was in grave danger of stripping the screws).
Gauges are easily visible from a normal driving position. Control stalks are definitely harder but not impossible to reach.
When it was finally securely attached and anchored down, I gripped the wheel, and gave it a hard yank...and immediately stopped, for fear of bending it.
It's most certainly not
as sturdy as an OEM wheel. I did not want to destroy it, but I'm pretty confident that I could taco the wheel if I really wanted to. It is absolutely not
an appropriate wheel for track use. If Braineack's similarly-styled eBay wheel is sturdier than this one, then it's made by someone else.
That said, I'm not entirely disheartened. For a street car, it'd be okay. For a street car you care about, it's pretty cheesy. But for a car that had a ratty, flaking, peeling OEM wheel and that you are planning on selling, it's just the ticket.
Moreover, it functions as proof of concept. I now know that the eBay hub works just fine for its intended purpose. I know that 340-350mm is indeed the sweet spot for me (at least for a street or dual-use car). I know that the deep-dish style wheel works well if you want to drive enthusiastically without inadvertently signaling a left turn or engaging the windshield wipers.
I also know that when I purchase a steering wheel for a Miata I intend to keep, it will be made by MOMO, Nardi, Sparco, or some other similar manufacturer, and I know that the horn button will not say "T-Horn R".
TL;DR -- The wheel is flexy. Don't buy it unless you are extremely cheap and undiscriminating.