Re-use or create new profile fields?

I am working on a D6-D7 upgrade project using Profile2 to replace Content-profile fields.
I have three new profile-types with many fields. Two of the profile-types use similar fields (name, address etc) but each type also uses different entity-references. I also have permissions set for every field so settings are getting quite complex.
I am tempted to set up new fields for each profile-type to keep everything separate, but I could also re-use some existing fields that are common to each profile-type. However I am not sure what the implications of re-using fields are and would be interested to know if anyone has advice or experience to share on this?
What's best, or is there no real difference?

Thanks