Also depends on what track you want the car for.

If the track doesn't have long straight areas or really wide bends I don't know how much enjoyment you will get on such a track from the GT3 compared to a Lotus (basically what I am saying if it's a high speed track go for the GT3 but if it's not the difference between an Elise/Exige and the GT3 on a slower track it's not that big in terms of sensations).

And from your words it looks like you are looking to find some additional fun.

Also don't forget that when you buy a GT3 you buy a package that was fine tuned so many years (for instance the GT3, GT2 and turbo are using an older engine block that is better and older in design but more expensive than the engine blocks used in general production C2/C2S/boxster/cayman etc.).

For pure high speed racing thrills nothing will beat the GT3 (maybe the RSR or the cup car .

The new R8 which I love it's a road car IMO. Same people that want to buy a Turbo or a Gallardo should look at those.
They are too GT for me. Not raw enough. think about it: AWD, DSG, electronic suspension and so on. You can train a monkey to drive such cars pretty fast and obtaining similar lap times every time. For example, all my friends from US, some of them Porsche drivers, they pick the non-PASM and manual versions of the cars.

But that is a matter of taste and frustration

Either for the people like me that are nostalgic and they want to have control of the cars or for the people that want to be "the king of the hill" just pressing the pedal to the metal and letting the car do the rest. But I still believe you want to be in the first category judging from your words.