I had this situation happen to me:
I had a complex type that has 6 properties and this complex type was used about 20 times in a single table. I had to go to the Mapping Editor and type in the mapping names for these 120 fields. This was very time consuming and tedious especially since that Editor doesn't make doing mass edits very easy to do.

I know Microsoft's Entity Framework designer will automatically do these mappings for you. It would be great in this capability was added to your designer.
Perhaps do something like:
Table.CPropIndex0
Table.CPropIndex1
Table.CPropIndex2
Table.CPropIndex3
Table.CPropIndex4
Table.CPropIndex5
Or have a more advanced feature that allows you to define some sort of naming scheme for these mapping names.

Also if I do change a name of a property that is a complex type it seems to lose the mapping names and you need to redo those in the mapping editor....