I bought a GT as back then, the GTD was still a bit new and used prices were commanding a much higher premium. It was for my wifes birthday, so I thought that the GT would do. If it would have been for me, I would have saved up a little longer and got the GTD.
The GT does look very ordinary, however when it is super shiney with it's Vancouvers sparkling, it does stand out a bit more, but not like a GTD would. Swapping for a touch screen radio helps to lift the dash board, but the standard air con knobs look a little basic.
Unless you can find a very well speced GT, I'd go for a GTD. All the the extras you would like can be retro fitted, so they can all come in good time as funds allow.