When you look at Millennium force, you think "wow is that steep!", but it really doesnt have a whole bunch of 80 degree track, more like .3 seconds worth. The advantage of this is that your already going quite fast by the time you reach the steepest angle. Because MF transitions to 80, and back, during the whole drop, you have that really smooth, naturally feeling drop.
Now take something like Goliath. It transitions to the 61 degrees almost immediately at the apex, and has about the whole drop at the straight 61 degree angle. I actually favor this better. This is why.
1. You get more of a lift entering the drop, and it makes the impression that it is more steep.
2. It gives you more of a natural freefall, if its steep.
If MF did this, it would be unquestionably better, but there's several obvious reasons it cant. Mainly the speed at the top of the lift, the trains, and because Intamin just doesnt like to do that.
Now a 90 degree drop highlights this perfectly, once we start seeing them on 400+ foot rides. I doubt a ride will have an overhang drop, so a 90 degree drop would highlight the angle by having a lot of 90 degree track.
Just some thoughts, what do you think?