The stock tow hooks are indeed strong, and it seems like you can crank down harder on them, but maybe that is because you are actually compressing the Miata's suspension as you tighten the straps?
I prefer to tie the car down using pickup points on the wheel-end of the shock/spring. That takes the Miata's suspension out of the equation. Front straps go through the front wheels and then straight to D-hooks on the trailer. Rear straps go around the bottom rear control arms near the subframe, get crossed, and then to D-hooks on the trailer.
The HomeDepot yellow straps will work just fine. I used 'em for years.
That said, I really like the Mac's tie-downs with integral axle strap:
Great quality, pick your own color, pick your own length, "direct-hook" option to really shorten the buckle side of the strap, and awesome customer service.
All-in price is on par with the HD yellow straps plus axle straps. Of course I paid shipping but didn't pay tax. The quality of the straps (2" is much nicer than the generic HD was; more pliable, yet very strudy).
My trailer box was broken into and looted about a month after I purchased my straps from Mac's. I called them to re-order and mentioned the reason why I was re-ordering so soon. They took pity and totally hooked me up with a deal and on top of that threw in one of their organizer/carrying bags "so you can leave your straps in your trunk instead of the trailer box next time".
Great products, fair price, A+++++++ customer service.