Ah, a thread I can contribute to
I changed up to a TTS after owning an A3 3.2 sline. The S3 was an option, and I test drove one. It just wasn't different enough to the A3 and tbh, the interior of the A/S3 is a bit dull compared to the TT. If you forget cost (so assume the cost to change is the same for S3 and TTS) I would go for the TTS in a picosecond, its a no-brainer. Practicality wise, clearly if you need the back seats that rules out the TTS, but it is fine for the occasional lift; boot-space is pretty good in the TTS and is one of the reasons why the TTS was still on my list and the Cayman wasn't - I can get my bike in the back no probs, not a chance in a Cayman
Just done over 1k miles in my TTS and its a blast, I'm absolutely loving every moment, there are just not enough excuses to go out in it. It also feels soooo much quicker than the S3 its truly amazing. And handling? Different planet to S3 I'm afraid; the TT is nothing like the S3 and is definitely not a golf underneath, it has the aluminium space frame and feels so much more balanced and composed. I have driven a BoxsterS and the TTS is at least on par, if not quicker, and without comparing both on the track, for everyday driving there is nothing between them imho.
I have the stronic aka dsg gearbox which seems to some like marmite, and having never ever had an auto box before I was as bit apprehensive. However it is a revelation, an amazing piece of kit. You have to get accustomed to it and learn its nuances, but when you do it is a pleasure to use. I was so fed up with with my in-traffic daily commute, particularly with the 3.2 as it could be, er, a bit vicious to pull away in first at times! The stronic solves that and I just drive the car now; If I want to get more (more? completely) involved with driving I just drop it into manual and use the paddles. Keep it floored and the upchange is seamless with absolutely no let-up in power, in a straight line it would get away from an equivalent manual, no question. Fun? Yes. Addictive? You bet!
My TTS already pi$$es over my 3.2 for performance (although granted the turbo power delivery is different to the more linear v6 and I wouldn't blame anyone for prefering the v6, I did until I had a few hundred miles in the TTS). Just need a few more miles on the clock and then a remap is on the cards, probably just a stage1 but that should see around 310ps...
Launch control vid