I've had Duke/Transmute work a bit, but only as part of a setup that already sank the potion cost. For instance, I had a Scrying Pool setup where Transmute was the only way to trash and I built a nice strong deck, before I could megaturn on the provinces, my opponent had bought too many provinces (5 I think, maybe 6) so I then bought three Dukes and the next turn crashed my engine by mass gaining Duchies and buying two more Dukes. I managed To get 6 Duchies and 5 Dukes which forced the opponent to stall at 7 provinces, I gained another Duchy and eventually bought two more Dukes and two Estates to get over 50% of the possible remaining VP.
I also had a game where I lost the split on Vineyards and had mass transmuted Coppers to power up the Vineyards with a big stack of Alchemists. I swapped over to Dukes, got lucky and managed to get enough VP to eke out a win.
Many, many more times, I've gotten a Transmute because I've whiffed on something bigger (e.g. Familiar) and tried to use Transmute/Duke to recover ... it rarely wins but is better than 0 chance from other setups.