The shape of the river style blade is made more for full paddle in the water use.
Where the play boat shape is made more to be used in closer to the boat with less blade in the water for more leverage to be gitting that vert.
That is why if you look at a Werner Player you will notice that the bottom of the blade at the shaft is narrower, And a Powerhouse is more balanced in shape.
The Werner bent shafts, the blades are in line with the index on the shaft where the AT's are offset.
But it matters more how the paddle feels in you hand.
The stiffer the paddle the better the power transfer from you to water.
The more flex the more power is lost in the pull of the stroke.
That is one of the reasons Werner makes blades of different sizes.
The Powerhouse is bigger than the Sherpa so puts more strain on you to pull it thru the water but doesen't mean you get that power in the stroke in return if the blade is taking more enegery from you than it is returning in momentum.
If you are feeling discomfort after paddling you need a bent shaft.
and get the right length shaft also, to long and it will put more strain on the joints.