My $.02, I would not worry about not having a machine which was not adjustable for depth using the remote. I use about 170 balls in my machine which I repressurize but which still have a good bit of pressure variation not to mention variations in how much fuzz they have left. These differences cause the balls to vary in how far they get thrown on my machine so that I am always having to move my feet for each shot even if the ossicilation feature is off.
FWIW, I have owned an SP Star since early 2010.
When should you serve and volley in doubles? Only when you want to win.