Michael_Andreas wrote:...To achieve maximum speed from a RAID0 would require a controller that buffers the data from the RAID stripes and provides it a full speed.
What is the actual data rate of your files? How many tracks are you running? Have you looked into proxies?
This is not really correct.
If you put 3 of those drives in RAID0 you will have 1.5GB/sec. Each drive will do its 500MB/sec and in this case SATA6 (6Gb/sec) connection is not a limiting factor (there is no need for any buffering). What you don't want to do is to connect eg. NVMe drive (which can d eg. 2.5GB/sec) over some "case" which is eg. SATA6. Then you massively limit speed of your drive. If you have motherboard with many SATA6 connectors you can connect SSDs and make software RAID0. Speed will scale linearly with number of drives up to some point (eg. 4GB/sec). Those SATA6 ports will be connected to some PCI-E bus and depending on motherboard you can hit limit earlier or later.
You can also get RAID controller and connect your drives there.
Most good RAID controllers are PCI-E x8 (so around 8 GB/sec). If you want RAID5/6 then speed is limited due to needed calculations (eg. R=6GB/sec, W=4GB/sec). For higher speed you need more RAID controllers or NVME controller, which is still bit new and expensive (some motherboards allow you to do NVME RAID0 but typically for limited number of drives). Enterprise all flash boxes can do eg. 18GB/sec aggregated speed, but those are very expensive solutions.
To answer original question: all depends on budget. RAID type is up to you. If you keep original source backed up I would do simple RAID0. Get many HDD drives (5+) in RAID, or few SSD (eg. 2+) or single NVME drive if you do small projects. You don't need to over-complicate things. cDNG or BRAW does not need crazy speeds.