You have two issues jacking up the end points, especially with a DX7

The more sub trim you have the less room you have at one end of the throw to keep from hitting the stop.

Any mixing that adds to the surface will blow past that 100/100 and if you have the end points run up to 150 it will try to over drive the servo. Heck even if you have them to 100/100 and thats the mechanical limit of the surface and add a mix it will try to push past the end point. Radios like the 11x have a limit adjust and a travel adjust and limit adjust is a hard stop for the servo no matter what mixing or sub trim is involved