most likely not - it's just strange that some cgpsmapper maps appear completely in lower-case (first letter capital) - same behaviour as e.g. latin1 - while most mkgmap created non latin1 maps are fully in caps without --lower-case option. The code page is correct however. This is independant of Mapsource/Basecamp/GPSMapedit - however on Windows 7 it seems to be fine. On devices itself it also seems to be fine.
Is there a list anywhere which devices are compatible/not compatible with --lower-case? Maybe this note about incompatibility is really really dated?