Very soon - going through final internal testing
Do either of you have any LDAP replicas?
Mluxton, 4.5.6 > 4.5.10 > 5.0.1 is a fine route currently.
Not 'technically' required, but it's best to get on the latest 4.5.x (whatever that is when your doing your upgrade) before the 5.0.x jump.