I have both. I have had other tuners/programmers and must say the Smarty and TST are the best. I like the adjustability of the TST. I program the Smarty on whatever level I see fit (if towing I leave it low, for example) and adjust the TST if I want more power on the fly.
Smarty seems to maintain exhaust temps better than the TST. TST seems to spike the egts way up when set high. Hopefully the bigger bottom turbo I just ordered will remedy that.
TST has the turbo cool down timer, fuel pressure adjustment, timing adjustment, egt high temp feature, and four different fuelling programs all on the fly adjustment.
If Smarty had these adjustments on the fly I would sell the TST. Though, I think the TST has better top end power.
Still testing the two. Always upgrading. Seems to never end. When I finally have the adjustments I need another company will come out with something better.