Pros and cons Tiny Cooling Fan in ball bearings

"Tiny Cooling Fan" Now more and more choice of ball bearings, which is the trend, then the ball does what advantages and disadvantages?
"Tiny Cooling Fan" The advantages of using a ball bearing
A metal beads belong to the contact point of the operation, so it is easy to activate operation
B can be used often placed at different angles and direction of the operation of the portable products (but to prevent disorderly fall or fall)
C long life (compared to oil-bearing)
"Tiny Cooling Fan" with the shortcomings of the ball bearings
A bearing structure is quite fragile and can not withstand the force of the impact
When B motor rotates, rolling metal beads will have a greater the noise
C high prices, can not compete with oil-bearing on the cost price
Source and amount of demand for ball bearings D, difficult to control
E elastic spring ball and it is positioned on the assembly more difficult