Actually, using one file for both kind of does create problems as it renames the linear survey features by adding a sequence number, if there was already a linear feature from the XIN link.
By using two files, I don't get the renamed styles.
However, I am not sure how the software deals with the extra feature names when saving survey to geometry of whatever other conversions are possible.
Lets say I have a CURB style from linked XIN and a CURB1 style from Survey Feature Definition "link". When I collect a survey using CURB as my alpha codes, Survey understands the CURB is the Code, but it gets saved with Style CURB1. Now lets say I save this survey to Geopmetry. Does it convert the Style back to CURB ? Or does it retain CURB1 as its style.
In Ss2, Survey, Surface and Geometry could all share a Style of CURB. And in Ss2, since Survey to Surface created Features in the DTM, we wanted the Survey Styles to all have a companion setting for the Surface Styles and generally, wanted them to be identical. This allowed us to edit a DTM if we found a bad shot in a surface from survey, without having to go all the way back to Survey and recreate the DTM all over again.
With Open Roads and the DGN being the new container for both Survey and surfaces, I am inclined to still want the same style names and symbologies but it's possible that I am overthinking this. That;s what happens when we undertake a paradigm shift in workflows and file management.