I was in a similar place a few months ago but have now decided to simply replace my T with the .2 car, as much as I like the GT3 I can’t see that it would offer me enough.
Personally I’d want a manual and as I would only track very occasionally I’d not bother with PCCB’s.
I would definitely want them on a GT3. They have numerous benefits that specifically suit road use. Not a cheap option, but worth it IMO Gearbox choice - auto or manual - is down to personal preference. No right or wrong.