I was an Audi/VW guy before I got into LR (and still am). It looks from the pic, at least the yellow (Boxter?) caliper and BBS LM's?... That you do indeed have the TT well sorted, without even knowing what you've done to the 1.8t.
That being said, my opinion would be to keep the TT. If it's a monetary concern straightening out the Defender, remember the cost of building the TT, let alone building another one if/when you got tired of the D90.
If you were closer, I'd say come take a spin in my GT3071R spooled, 1.8t '83 Rabbit. It's kinda nice having a little of the "Best of Both Worlds"