I'm on version 4.7 of SAP EHS and we are initiating a study to see how long it will require to upgrade the version of EHS to ECC 6.0, someone has gone through something like this? How long did it?
I just was part of a technical upgrade from 4.7 to 6.0. This was not only EH&S but all of SAP (as far as I know) and most parts were heavily adjusted to customer-specific needs with a lot of RICEFs involved. Only the upgrade itself including all the testing of course was almost exactly one year. I have no idea how long the planning phase was, I guess at least another 6 months. However, this was a monster project, only upgrading EH&S will take a lot less time.