Re: SRT-6 vs. GTO
If the small interior size is a big concern for you, don't get it. On the other hand, if you've had any small two seater for a time and adapted, the SRT-6 will feel very comfortable.
Some people get small two seaters, and find the dimensions make them feel more connected to the cars and the road. Larger people with that outlook have happily squeezed themselves into smaller cars. But some people never do and just find them claustrophobic. Your gut tells you which camp you fall into.
If you're in the second group, don't talk yourself into anything. It won't get any bigger the longer you own it.