Don’t have a cage but I have a HD single diagonal roll bar in the Yata and fixed back seats with higher-than-stock bolsters (Corbeau). Ride height is low, but not disgusting. For winter I have it at 12.75" hub center to fender.
Anyways…
From daily driving this car for the past 2 years, here are some issues with the roll bar / seat that I notice compared to stock:
If you have a zippered top like I do, forget ever zipping or unzipping it with one hand. With the seats you can’t turn towards the rear and the bar is in the way anyways.
Ingress/Egress is affected primarily by the seats.
You have to kind of make a slow “roll” into them after putting all your weight on the left leg and then bending down low to get into the car. So when passersby whip out a camera phone it’s not 'cause your Miata is so damn DOPE- it’s because they are laughing at what looks like a beer-bellied human emulating an ostrich taking a dump- on one leg (in my case).
This is good if you are an attention seeker or, are a right handed basketball player looking for iLL hOpZ on your layups. $hit, another year of this left leg single squat bizness and you may see me on Youtube taking Vince Carter to the hole.
Now for clearance issues.
If you are 5’8" or above and on stock seats, with a helmet on you will probably have just enough clearance between your noggin and the bar to slip a manila envelope (preferably with a blank check in it already made out to the hospital of your choice, because that’s where you’ll end up when your shocks bottom out and UNGH straight to the cranium baby).
Solution: get aftermarket seats that place you lower in the car, buy padding, and return Ebay coilovers that run on bump stops all day…
With the bar- YES the car is stiffer, NO I cannot feel it when I’m plowing 7 inches of snow in front of me gingerly turning the wheel into the apartment complex at 3.6 miles per hour.
But I wouldn’t have it any other way.
HOWEVER, the extra bars in a Spec cage would just be too much for the street. Getting out of the car would be akin to crawling out of a train wreck at that point.
I say go for the roll bar over the cage. Cheaper, safer, and much more usable.