If you get a GTA you will find the nice roads where you can really enjoy it within legal limits. You don't need to drive at over 80 to enjoy it (in fact I find that boring because it's just cruising). It's a lovely torquey engine that delivers the power all the way through the gears. I got to near 7000 rpm in 2nd and 3rd legally today and it was fantastic!
They are more costly to service than a normal 156 but if you get a well sorted one they needn't be that costly. Alternatively, get a bargain and be prepared to invest a bit in it and you will be rewarded with a very special experience. It's taken me a year to get mine to where I want it, I plan to keep it for another 4-5 years, at which point I reckon that 149 GTAs will be about 2 years old (and that's my planned replacement).
There's loads of good advice in the GTA section, including a fantastic buyers guide by Chris155 IIRC. Just do your research on this site first so you go in with your eyes open.
Even though GTAs are becoming more affordable, they will remain a relatively exclusive club because there were not that many of them in the UK.