Preacher you asked to hear from a flatwater canoe racer so, from someone with limited race experience and plenty of bent shaft experience:

Bent shafts have nothing to do with correcting technique.  They just make proper technique more efficient, because the paddle blade is kept perpendicular to the water.  As a result, they reduce drag, increase speed and reduce fatigue.

Traditional paddles create a lift on the boat in entry , because the blade pushes down on the water and in recovery the blade forces the boat down because the blade is pulling up against the water.  Proper techinque will minimize the results, but regardless, the stroke is most efficient when it is perpendicular to the water and bent shafts allow the paddler to stay perpendicular for more of the stroke.

If that doesn't make sense, give it a try.  Get into a good strong cadence and you will probably notice when using the straight shaft that the canoe will seem to "Bob" up and down a bit or surge forward.  Then try a bent shaft and notice how the boat smooths out and seems to glide better and increase in speed.  That is why "racers" use them.