Based on driving one SLC around for a while, I think the biggest issue for a daily driver will be sound management, followed by sealing the car from air leaks.
Actually driving the car is pretty enjoyable- the ride is good, brakes are great, and steering is direct. And of course, it's stupid quick. :laugh:
But a typical side exhaust with a mini muffler will be painful unless the car is sealed up. Rear exhausts are much quieter, in my experience. And the aluminum firewall makes a great drum, so dampening that is crucial. I think extensive use of Dynamat or something like that is essential for a street car.
One thing I think distinguishes a street car from a track version is the use of sealing around the doors and the body/chassis interface. Some production cars have multiple seals around the doors (my Touareg has triple door seals and can ford streams up to 20"

) and my SLC will have a similar approach to sealing. If you don't seal the body to the chassis carefully, air infiltration will start to compete with the car's heater or AC systems. And of course, that same gap that lets air come in does the same for water as well.
Once the sound and infiltration issues are resolved, the only things to watch out for are clearance-related.
Also, a real DD has a way to lock the doors when you have to leave it to run into the store, or at work, and I haven't seen anyone do that yet. You could add the Mazda door cylinders and keys, or use the included bear claw latches to operate from the ISIS system with the addition of a couple of small solenoids.
And then, aside from the constant camera flashes and delays at the gas station while a million people ask you "What's that?", you will have a great DD.