I agree with Longwinters for the most part. I have a BowTech that is rated around 323 fps. With my arrow I should be getting between 280-285 with a 560+/- arrow. "Properly tuned" I have no problems with 125 grain 2 bladed stingers. Improperly tuned, like Longwinters stated, with that speed you can certainly screw up a whole lot more.
The BowTech is surprizing quiet. But a bow of 250 fps is not going to be bad either. The difference between 70 + 60 pounds with my bow is only about 10 fps and 11 pounds of kinetic energy. I shot 2 bears this spring. One with a old Person at about 220 and one with the BowTech. The first bear ran 40 yards and died in 20 seconds, the second 20 yards and died in 10-15 seconds. Both bows gave me a complete pass through, lung shot each.
Moral of the story is that what is important is not speed, but where you put the arrow. It is like the gun writers pushing the new short magnums. The deer just isn't going to know the difference if it is hit by a well placed bullet at 2,700 fps or a bullet at 2,900 fps.