Hi CC_Merchant, thanks for taking the time to respond.
I had a feeling dual GPUs wouldn't be that much of a benefit.
As for the striped array, the data on them would be backed up on 2 separate externals (not matter what internal / current project HDD set up I go for, ALL data would be backed up externally)
I had discounted a raid controller purely to keep costs down, but will look into it again.
Cheers