Hey,

I used the Hitech 625 all around using 6 volt battery since they have speed which is required for 3D. 645 are not as fast. The reason for digitals is not only are the more accurate but the torque rated for the servo is 100 oz. through out the entire movement of the servo versus the torque on the non digital is only on the end of the movement. It builds up to 100 oz.

1.20 size 3d planes are boarder line for digital thats way you can get away with a mix of the two.

Once you get into 3D 1.20+ planes you are now investing in radio gear. It is the best size for growing and the investments can be done in stages. 3 digitals and 2 non digitals is cheaper then 5 or 7 digitals with larger planes.

Hope this helps.