I have done it and actually changed the Intergroup to a new IPE. It was very easy. It took us about 4 hours to complete the card cage upgrade of the core modules and the FIJI upgrade. Now we only had two network groups, so take that into consideration.
Changing the Intergroup to an IPE took about 45 minutes, but that was because of the darn ribbon cables. It was an easy backplane installation.
No issues were encountered, and it all went a lot smoother than we expected.
John