RAID 10 vs RAID 5 (12 disk)

Hi,

I have a new VNXe 3100 with 12x 600 15k SAS disks.

Space is not a problem for me, as I have plenty, so I can decide if I go with either (3x3)x2 RAID10 (no spare), (4x1)x2 RAID5 (2 spares) or maybe even (4x1)x1 RAID5 and (3x3)x1 RAID10 (1 spare) configurations based solely on performance and reliability. Maybe someone can help me with this decision.

What I would like to know is:

a) How unreliable will be RAID10 without spares compared to RAID5 with 2 spares? We have Premium Support for VNXe, but only business hours availability from our side.

b) Does VNXe RAID10 implementation reads from both disks on a mirror, or just from one?

c) What would be the read IOPS from both configs?

c.1) Will RAID10 give me 12x(read IOPS of 1 disk) or just 6x(IOPS of 1 disk)?

c.2) Will RAID5 give me 10x(read IOPS of 1 disk) or just 8x(IOPS of 1 disk)?

d) What would be the expected ballpark random write IOPS from both configs, considering the VNXe 3100 8GB config (~1GB cache)?

e) What config would you prefer, and why?

Thanks.