The numbers don't lie. Insofar as Dwarves (or any other Race with 6 or less OP/unit) are concerned, Stables are a smart choice. For Races such as Orcs or Undead (with their 9 OP Elites), what you say is entirely true - the OP boost from TGs is more significant than what Horses offer. But we're talking Dwarves here.
Sciences have been between Active and Accelerated since OOP. The only Dspecs I've trained since OOP were with the free training credits from attacking - everything I've actually spent money on has been Zerks (and a few Thieves).