Let's get back to the fundamental question. Why should the pockets for pro pool be significantly tighter?
Is it to substantially reduce the number of open table runouts for pro players? Do we actually want to see more misses by pro pool players on relatively routine shots? Do we want to see pros choose to play more safeties on fairly tough but wide open shots (maybe because they're unable to cheat the pocket and get position or they're simply afraid of missing a table-length shot)?
If the reason for much tighter pockets is for the cream to rise to the top, I argue that the cream will rise to the top regardless of pocket size. The cream will eventually find a way to win (maybe after some adjustment). But with much tighter pockets, you simply make the game slower, more painful to watch, and something that resembles pool played on Chinese tables.
If it were entirely up to me, for pro events I'd keep 4.5" pockets and switch to 12-ball.