Go for it, but to play it safe work for maximum mechanical advantage.

To get this:

Set your Transmitter servo endpoints as high as it will go on the TX ( I use 150% on my JR radios ).

Move the linkage connection on the servo horn in at least one hole over what is recommended or if possible all the way in ( towards the center screw hole ).

Move the linkage connection the the control surface horn out at least one hole more than is recommended, or if possible all the way out.

Adjust the linkages and hole positions until you obtain the indicated surface deflection amounts.

This will give you increased holding power, better servo resolution and control, while demanding less from the servos themselves.

Turn up your TX's expo for even better fine control around stick center.