The "E-props" and slow flyer props are similar... The 10X4.7 is intended for a very slow flying model, making good static thrust but not provinding must top speed to the airraft. The 9X6 e prop would reduce static thrust, but might help you maintain airspeed at the lower throttle setting.

Electric props are not as strong or as heavy as those intended for glow power as the electric motor does not have the power pulsing of the glow engine. A glow engine would snap a wood "electric" rated prop.

You should find some difference in the 9X6 E and the 9X6 slow flyer prop too... again it will be in the weight and strength of the prop. The slow flyer prop will be lighter and more fragile, getting closer to looking like a rubber power prop with a large shaft hole. The "E" propis made for a stronger, higher speed motor, the slow flyer prop is made for the litttle 280 and smaller motors and may be expecting a gear reduction to keep the prop within its designed tip speed limits.

You can stick a "E" prop where a slow flyer prop is recommended. the only real penalty doing this is a small amount of weght.

You can not stick a slow flyer porp on where a E prop is recommended.

Go ahead and try the 9X6 E rated prop. It can't hurt. You may find that clmb rate suffers... You may find that all areas of performance are so much better that you stomp on the 10X4.7...