I want all PEOPLE in the same place.
It's very inefficient for Leads to be separate from Contacts. They should all be contacts, with "Lead", "Friend", "Info Source", "Media Contact", and other custom person-types in a "Type" field.
This is evidenced by the fact that you can convert a Lead to a Contact, but not back to a lead. You should not have to "convert" anything, just change the contact Type from "Lead" to whatever.
You should still be able to view and perform various special Lead-Only functions and features on "Leads" only.
It is also inefficient to have "Accounts" separate from "Vendors". Yes, you should be able to view them separately, and perform special functions and features that only apply to "Accounts", or only apply to "Vendors". But they are both COMPANIES, and should share entry forms and database table, with a Type field set to "Vendor", "Account", "Media Outlet", or other custom company-types.
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