I processed a 112 JPEG DTM. I had 6 GCPs and able to tag GCPs in 47 of the images. GCPs were taken with a RTK GPS system.
I processed with the GCPs translated to WGS84 CRS, but kept the elevation in elipsoid units.
The DTM GSD was ~ 12".
When I checked my 3D accuracy against the GCPs, the error was dominated by elevation error. I’ve included a picture below of the elevation error by GCP in inches. The X/Y errors were small by comparison. Roughly 1/5th the size of the elevation errors at the same location.