Thread: using a mixe of HERE and TT maps possible?

The weight of the HERE and TomTom maps files being very consistent (several MB), the idea is to optimize the use of iGO (fluidity and light). So, I'm looking to find out which files are "common" for HERE and TomTom maps in order to use one or the other but not both at once.
I know that the maps landscape dem are common.
I guess fbl, fpa, fsp, fda, hnr, ftr, fjw files are HERE or TomTom specific, therefore not substitutable.
On the other hand, I think that the buildings 3dc and 3dl files are not specific and can substitute one for the othe. Isn't it?
Regards