Adding more segments to key flexfield 'Item Categories'

We have been asked about the feasibility of changing our current key flexfield Item Category structure from 2 segments to 4 segments. Our response has been that, since we have operated with our current setup for a number of years, this would be extremely difficult to do. As a result, we have suggested that this shouldn't be attempted because of all the potential impacts in both our Inventory & Purchasing applications.

However, all that said, I'd like to ask:

• Has anyone actually attempted to do this themselves &, if so, what problems did they encounter?
• If this isn't possible, is there an alternative approach that we can take?