How long of driveway do you have? My dad has the county plow but his driveway is over 100 yards and he can get going some good speed to fling in into the ditch. If all you doing is residential driveways and you don't get much speed, you are just pushing to the edge, go straight blade.
The tapered part of it only works well when you have the blade angled, but when it is angled the blade wont push piles around.
I think the tapered blade does not work as well as the straight blade. When you make the first pass with a tapered blade it will spread the snow. After that you need to keep moving the snow to the sides. A tapered blade will only allow you to move the snow in one direction if you only use half the blade. If you hit it straight on it will push snow to were you already moved it. The straight blade will allow you to move more snow to the sides by having more blade to work with.
The tapered Plow is way better to plow with in my opinion, I have used both quite a bit and I would go with the tapered blade all day long! The tapered has more surface area which = more snow pushed. With the straight blade I found that the snow wanted to roll up and over the blade so I installed a rubber flap to discourage that and I installed a piece rubber on the blade that allows for the blade to glide over imperfections in the concrete.