Personally I would cut your losses with the 7400 ... yes it will do want you want, but why would you want to run a business critical function on unsupported equipment ? (and already old equipment)
- I'd also hope you aren't planning on hosting your own customers VDIs on the array, that would be dumberer.
If it were me ... I would return the 7400 to where you got it for a refund, then approach one of the smaller NAS companies (Thecus aren't too bad for performance and price, synology and Qnap also do good SMB sized units), get yourself something that doesn't rely on support forums to make it work and comes with a nice new warranty.
10Gbe iSCSI works very well and is cheaper to implement than FC, the Starwind product you have should work fine if setup properly (you went free or paid ?).
Reading my post it does come across as negative sounding
I'm maybe trying to say that spend the effort in designing a solution that will work, then spend the money .. 80% design, 20% implementation (not the other way around).