An oral won't improve the training offered in Part 147 schools, but it could improve the quality of licensed engineers, if done properly.
In the UK, the difficulty is that an oral is only as good as the examiner, and the days when you got a job with CAA because you were the best have disappeared. Now the majority are unemployable anywhere else, especially in PLD.
Judging by recent history, the chance of attaining consistent standards, let alone adequate, experienced expertise among CAA oral examiners is zero.
And how about the other 26 States? Would their orals be exactly the same standard as everyone else's?