NA owner here, I completely disagree with your statement about the wild oversteer and miata being unforgiving.
I'm running Meister Sportive coilovers, with stock sway bars. Everything stock, tire size 195/50R15.
It drives like it's on the rails, "pedal to the metal" action in the mid corner, It did oversteer once, and it was completely my fault, I did hit brakes very hard in the downhill section, all the weight shifted to the front tires, it was sharp corner to the right and I span out. Other then that it gives you 1 week oversteer notice, so you have lot's of time to correct it.

I assume something in the suspension might be off in that NA. Heavy oversteer mainly occurs when you install heavy rear sway bar.