Extending Profile Types with related data

I have a 5 profile types at the moment and in one of them I need to have some form of master detail capability which allows the user to CRUD against another data in the database, a 1-n for instance. Example.

Profile Type: 1
Username: user001
Firstname: Geoff
Lastname: Davis
Favourite Color: Red

PropertyCode    Description
12345                Property 1
34848                Property 2
28394                Property 3

Profile Type: 2
Username: user002
Firstname: Another
Lastname: User
Favourite Color: Blue

It seems to me that I cannot really leverage the profile types, registration and profile widgets for performing this capability so does this mean that I should really just keep the membership simple (username, firstname, lastname) and provide my own userdetails (userid, faviourite color) and userdetailsproperty (userid, propertycode) tables seperately?

What would you do?

Thanks in advance.

Geoff.