I run my two LSI cards in HBA mode. The initial minor annoyance that I had was having to flash the cards in. Which coincidentally was also my first time ever doing something like that.

Do you have any experience with hardware RAID provided by motherboard manufacturers like Asus? I have a spare dual xeon system I may utilize for my next NAS build and I'll pair it with two more RAID cards that can be put in HBA.