The 1.5" arms work BUT you have to be careful with them as you loose 50% of the FORCE the servo can drive. Therefore Scott does not recommend there use. If you have multi ganged surfaces you can likely use them. What is the application, control arm length from hinge line to control link pivot point.

Another consideration is the Hitec digital can travel farther than other servos, they have a maximum travel arc of 180 degrees compared to 120 of all the rest. BUT it's not all usable as you get deminishing returns as you get close to 80 degrres in one direction.

I rarely have a problem obtaining maximum throw with the Hitec's and 1.25" arms...