Well I just did a little R&D for you on the good old GT5
Setup specs:
Playseats Evolution GP seat and stand
Logitec G27 with mounted H gate shifter (everything bolted to the seat/stand)
26" 1080p (~5' from seating position)
Both cars ran with sports hard tires (comparable to a high-performance all season)
Manual, no driver Aids exc abs set to 1
Tire wear & fuel consumption on
Grip reduction @ track edge real
Mechanical damage high
Three laps for best time
I just sent the '06 S2000 and '12 86 GT around Spa-Franchorchamps and here is the result I came up with:
S2000- 1:55.678
86 GT- 1:59.241
Spa is a track that favors higher- horsepower cars and accordingly the S2k had about 40 more with ~1000 more rpm to play with. Off the bat, the car is quicker. The 86 GT is no slouch though, it will come out of corners with as much brunt. Now, the S2k was the harder car to drive fast. Why? For starters, it is a convertible so right away rigitity is sacrificed and the need for a stiffer suspension is critical. However, the suspension is so stiffly sprung, the car has some nasty oversteer habits. This is in the form of both off-throttle-snap-oversteer and initial turn-in oversteer after braking. The only time I encountered on-throttle oversteer is after a small-radius corner that usually involved second gear cornering. So in general the car has mixed-emotions with it's own suspension, ranging from stiff and precision cornering to dogging the rear out as if I meant to throw it out. The next problem with the Honda was the power band. If I was not in Vtec, the car was slow moving and slow accelerating. Now, this did not happen very often since the track was more of a high-speed high-rpm course, but there were times where I was waiting for the car to get moving again.
Now for the 86 GT: this car is pure joy. Yea the s2000 was fast, but I had to fight the car more than I just drove it. With the 86, I could drive the car flat out every corner. There were corners that I could balls out go through that in the s2k I had to be gentel in otherwise I would be fighting the car in oversteer. The 86 was 3.563 s slower around the whole course, but I never had a moment of 'oh shit'. I felt happy every corner and I would prefer the 86 over the s2000 on the track for that reason. In stock trim, obviously the s2000 is going to be faster. I'm pretty sure we could all have guessed that one off the bat. But since when has driving cars for the numbers ever really been the main goal of the experience?
If I were you, I would just take the BRZ, and love the new car for what it is. You will eventually get annoyed with certain apects of the s2000 that can be avoided with the BRZ. It happens to everyone. There are certain things I have to deal with at times in the FC, primarily if I ever want to take a third person along, it just simply cannot happen. Now the trade off is I have a ton of cargo space. But there are times that I wish for refinement and other things, and that is why when I have the money, it will be spent on getting a BRZ and making the FC into a track day special. I can love more comfortably every day with the BRZ than I could the FC, just as you will find with the S2k.
Now you can take this all for what it's worth, just being a video game, but aim a believer that you can feel real world results just from blasting around the track in a sim such as gran truismo, granted you have all the right gear. My gear is about mid-range compared to what I could be using, but the results are still great.