it seems that the missing battery buffered cache has caused the performance problems
with the replication.
we have installed several open-e SAN's base on HP Hardware (most DL 360/380 G5/G6/G7 - sometimes with additional MSA 60/70) with replication in the last 12 month. either iSCSI oder FC - no problems with the replication performance (ca. 80 -90 MB/Sec).