I was looking into vol move and found this myself. One thing I did come across was this, but it didn't apply to me as I am not using a mirrored aggregate. It seems to apply to you though. I am not sure about the consequences of this, but it is a documented option.
The -o option is provided to ignore the redundancy
characteristics of aggregates in Metro Cluster
environment when vol move is initiated from mir-
rored source aggregate to an unmirrored destination
aggregate. In other words, without -o option, vol
move will not start and if started when the redun-
dancy characteristics of the two aggregates were
identical, will pause if the redundancy character-
istics differ before entering cutover.
- Scott