I can answer the difficulty question fairly well. The Gen III is much easier to drive on the track than a Gen I or II. I find it to have much more progressivity and predictability, both which allow you to approach the limit more closely.
However, even with the easier aspects I find myself leaving pretty large margins when on the track. An example is in the braking. I can reduce my brake point by over 100ft for a typical turn at Gingerman, but I leave myself a greater margin than I did before, generally leaving an extra 25 to 50 ft before turn-in. I have not yet gained the confidence to take it to the limit for braking, though the braking is just phenomenal.
At Gingerman the acceleration is not that much different as the Gen III has a gearing disadvantage versus the Gen II (Gingerman is generally a 3rd gear only track). The only place where I find a slight advantage is on the front straight where I achieve a speed in 3rd that is above redline in 3rd for a Gen II. But I think that is the only advantage for acceleration, unless the car is regeared.
The other main improvement is the ability to take corners closer to the limit due to better feedback and predictability, something that is totally lacking in my Gen I. I find the turn in speed capability of the Gen III to be quite a bit higher than the Gen I/II. And when you find yourself surpassing the limit you can scrub some speed off while maintaining control.
All in all I think you should be finding some more capable SRT's over time. You may find the more track prone owners will stay with the GTS until a hardtop version of the SRT is available. The roll bar restriction is severe as most of us are not willing to give up the stock nature or useability, let alone the spend the money on a non-performance oriented improvement.
Checkmate.
