I found my TT made a difference all the way up until I got the access tuner software. Once i had full control, I don't think its needed. But even with OTS tunes, it helped.
Access port is such a polished and nice setup, I can never argue with it.
If all you plan on it an air intake, catted downpipe/catback, and intercooler (basically stg3), i'd say you could buy the TT and grow with it all the way up until you decide to get a pro-tune. Then you can always re-sell it for $100. I mean... $200 total investment ant bad when $300 CAI's are out there.
All the way up until I started tuning my own car, I had it, I used it, and it worked great. Anymore than that; and I'm not much help.
As broke as I am, if I came across the TT and knew that I had no choice in the next 6 months to spend $500-$650, but I could squeek buy on a TT, then I'd do the TT again. But your right. $200 now to spend $500 later, maybe not the best plan.