Trimble Business Center

We seem to be having some trouble with georeferencing our scans. I'm posting the steps of our work flow below and the equipment we are using.

When we attempt to georeference to set survey control, we end up with tenths in residuals. Once we change the coordinate system from default to NAD83/2011 our residuals reduce to hundredths and are acceptable. My question is why this happens? 

Georeferencing residuals should remain consistent not matter the coordinate system since the units are still survey feet throughout. However, changing the coordinate system in the software seems to make a difference. Why would changing the coordinate system, change the distances? How should we proceed to avoid this issue?

Equipment: Trimble X9 

Processing Software: TBC

Note: In the field we shoot precision points to steel targets on survey rods, set over control for georeferencing.

1. Create new project
   1. Units: US Survey Foot
   2. Coordinate System: Default
   3. Grid
2. Drag and drop TDX file
3. Register/refine
4. Import control coordinate txt file
   1. Control is in Maryland NAD83/91 or NAD83/2011
   2. project remains in default
5. Georeference