we have 3 BM 3.8 Server on Netware 6.5 Sp5 and want to upgrade to 3.9.

Is there a Overlay 3.9SP1 to be released as mentioned on brainshare this year.
Are there any severe problems left with running 3.8 and 3.9 parallel in the same tree .
We have ou and server based acls and i´m not able to upgrade all servers at once.