Believe what you want. If you listen to Dave Patrick you would have $1000.00 in servos on a $300.00 airplane. MOst people don't have the money to burn like that.

2 servos work just fine on this plane. In my opinion the simpler the better. 2 more servos is just 2 more servos to go bad

If you use 4 servos you will have the same amount of control rod connections as you would with 2 servos. So the theory of less connections with more servos doesn't make much sense.

All you need is the correct amount of torque and no flexability on the control rods. It doesnt matter how many servos you use.

Speed is another question. Speed depends on how you want to fly the plane. The average flyer doesn't need or want fast servos. Fast servos will only make the plane more sensative. A slower servo will make the plane more smooth in flight. If your flying 3D a faster servo will help. It all depends on how you want to fly and how much money you have to burn.