i really want to use omv6 with small hardware and raid1. what would you prefer ?
It's all based on your needs.
As mentioned by ryecoaaron (I agree with his statements), there may be limitations, if you have to use a NAS in heavy mode with some heavy services, you need something more robust (eg: a Mini ITX motherboard with 2 or 4 SATA ports for better reliability).
And remember that a RAID array is not a backup, there are somewhat more complex solutions (such as RAID 5 or RAID 10) that are also more robust.