I don't think the DX7 has servo match - haven't come across it in the manual nor anywhere in the TX.

I'll look at the servo linkage some more.

During the downward part of the loop - I only have a slight up pressure on the elevator (less than a 1/8 input) and as I finish the loop I give it a tad bit more up elevator to level her off - thats when it tips - but i'm only giving it - maybe - quarter input. I checked the throws on the ground with the same (approximate) inputs and the differance is very minimal. I see the differance at the highest and lowest but not in the middle. Can that slight differance in the middle be enough to make the plane tip? obviously, something is going on and I will double check my linkages.

I have DS821's on all sufaces and the rudder is the HS-5625MG. Powering it with an OS FS91 surpass III w/ pump. spinning a 14x6 Master.