Upgrade effort for 2.3 to 3.1

[pludi]

After a long struggle (with support by our help desk) we've managed to persuade our management into allowing an upgrade of the internal OTRS system to 3.1. But not without an cost estimate. The current system is OTRS 2.3.4 with ITSM 1.2.3, which started as a OTRS 1 (upgraded by my predecessor). There's been a lot of experimenting, and the internal structure isn't quite professional. My questions are:

1. Would it be better to upgrade the system, or build it fresh from scratch?
2. Is it possible to import ticket information from the old to the new system (DB dump maybe)? How complex would that be?
3. How reliable is the SSO solution described in the Wiki?

I'm grateful for any information you could provide.

[Jodiazio]

Would it be better to upgrade the system, or build it fresh from scratch?

It doesn't matter