Replication Scenario

I have been fighting with the different types of replication but I am not finding what I need. Here is my scenario. Can Open-E provide this functionality?

Two Open-E Systems at different locations.
The locations have a VPN connection between them (1 mb thoughput).

I would like to have one system replicate a nas volume or iSCSI to the other system. Does not need to be real time. I would only like to replicate the data every night from 1:00am to 6:00am. (during this time the ISP doesn't traffic utilization)

(This is strickly to protect important data from building loss due to fire,etc)

What I am finding..Correct me if I am wrong

- Asyncronous Data Replication - Can't schedule this based on start and end time.
- Asyncronous Volume Replication - Not supportted - although I swear I saw a checkbox in a prevous version that would allow this to be Asyncronous.

Any help or direction would be greatly appreciated.

Due to problems in implementation and performance, async has been removed.
It is going to be added again in the future, but I do not have an ETA yet.

With sync rep, once its consistant the speeds will increase, and sync randomly through the day.