I had this dilemma when I owned my aero, I just couldn't decide if I should go NA-TT or NA-T.
I was always in contact with Keron about doing a TT conversion, but after 7 years ownership I wanted a 6 speed too. There were no TT engines with 6 speed gearboxes being broken at the time, so after saving some money I sold the aero and bought a TT6.
Being an aero, if you're desperate to go TT do it. As I can understand you doing it with an aero rather than an NA hardtop. In the end I just thought it would be easier buying a genuine TT and I lost patience waiting for a TT6 being broken