I am confused as to the differences between the HPP-20, HPP-21, HPP-21 Plus and HFP-25 servo programmers. The on-line manuals seem to be geared toward users that are already familiar with servo programming. I have some recently purchased HS-5625MG servos and need to figure out which programmer is best suited to my needs. I am most interested in being able to reverse the servo rotation directions, increase the angle of rotation to achieve maximum control surface throw without overtaxing my servos by resorting to extreme control surface linkage geometries and coordinate 2 servos such as using one servo on each elevator half. What is the maximum angle of rotation I can safely program the HS-5625MG for? I am not particularly interested in being able to do any field programming or testing.