The suspension and braking are fine to spirited street driving imho. The power feels... too easy. It's not slow by any means, but dropping the hammer is a dull affair because its just so effortless and controllable. The car is a lot faster than it feels so if you are used to a brutal supra which actually feels wild, it's going to be a snooze when open it up. Because of this i feel you need to tune the power for the car to feel alive.

 

I had a Supra as well...When heavily modded and power far exceeds what the rest of the car was intended for (stock), it can get a bit wild and uncontrollable.
Chassis and suspension didn't feel as tight as the 997 but mine had a targa and the technology was older.
No doubt a 700 HP Supra is fast but you can easily make a 997 turbo just as fast..plus it'll have better manners. A modded 997 turbo will make a great stablemate to your Supra.

 

GTR is a great car as is the 997TT.
Do test drive as they are different animals.
GTR might be a better daily if rubbing/bottoming out is an issue where you drive.