ARC1680ix vs ARC1261ML performance wise running SataII's?

Anyone happen to know how these two compare benchmark wise when
running Sata drives.. i'm torn between them.. for now we will use SATA
drives, but despite having the sas backplane on our supermicro chasis,
the 1261 wont be able to do SAS drives (from my understanding)..

Some have suggested going with the 1261 if doing sata.. but i'd like
to see some real benchmarks etc..

Our server will host about 40 users, probably only 20 at a time if
that (virtual server hosting on raid6).

Thanks in advance