I have always set up my gasser throttles with differential though not quite to the extreme shown in the diagram. I prefer to have a fair amount of adjustment towards idle so I can adjust the end point there and allow for a throttle cut at that end of the travel. As a result, my servo arm is not parallel to the servo body at idle but at maybe 20 degrees or so. I've always found that differential prevents the "toggle switch, on or off " effect that gasser throttles can have if everything is set at 90 degrees as you would with a glo engine. In many cases, with mechanical differential, no radio throttle curve is necessary. I did this long before our radios had a throttle curve available in aero mode.

As for the throttle springs overloading the servo ...... that has long since been debunked. Use an amp meter and measure how much your throttle servo draws to overcome that minor spring tension from the carb. It is minimal at best and far less that what any servo draws on a flight surface. I see no reason to ever disconnect a throttle spring and in fact can think of quite a few reasons to leave it in place. This is just another one of those subjects that has been discussed until the horse was beat to death. Quite a bit of real info out there if one is willing to do the searches so I will leave it at that.

The main thing about any gasser throttle is you NEVER have to adjust either servo endpoint to a stop resulting in a servo stall / overload. At a stop servos can and do fail from electrical overload, motor failure and even gear failure. This is the main reason so many people insist on metal gears for a throttle servo .... poor installation!