We had a DL380G5 with 7x500GB SATA SFF (2.5") and P400 controller as testing platform.
The performances was substantially lower then SAS, we had a hdparm write ("hdparm /Tt /dev/sda" in linux vm) value around 60 compared to 160 in the same machine with SAS disks. Performance are acceptable if you don't go in production environment with many vm.
The best thing you can do with HP G6/G7 platform is to raise the cache of P410 to 1GB or at least 512 MB (BBWC is mandatory).
I hope this helps.