Supershifter2 brings up some good points. What is it you want out of the car? All of your options have pros and cons. Everything from comfort to routing exhaust. What works on a track doesn't work over pot holes. How well the design is executed is more important than what type it is. And there is a HUGE range of quality in shocks and springs. People think they can get by with KYB shocks and cheap springs. What can be done with the stock design would surprise most people. BUT this isn't for everyone. If you have a reason to leave the stock stuff behind, then do it.
My car will never see a track, but it does see a lot of mountain roads (with $$$ german cars). The t/a made the car smooth and predictable.
Now that you've said you want coilovers in the front, that throws a huge variable into the mix. Front and rear have to work together. What is the plan for motor? Why do you want c/o in the front? Mod motor, better motion ratio, ride height adjustability, bling?
There is a guy on modded mustangs . com that uses the tci, tcp and possibly R&C stuff. Look for mustangone.
Supershifter2, If the T/A adds weight, it's not much. My fat, heavy convertible weighs 3533 with me, full stereo (subs) and 20 gal of gas. I wish I had corner weighed it with leaf springs, but didn't.