Hey, I'm building a computer with lots of storage, you sound like someone who knows what they're doing... maybe you could help me... currently the plan is:

3x Firecuda 4tb NVME

2x QVO 8tb SATA SSD

4x WD Ultrastar 18tb.

My use case is I need tons of storage that operates fast and is used for all sorts of things (creative work, gaming, archiving, job processing), sometimes all at the same time. It's a threadripper pro workstation pc, so I have spare PCIE slots to upgrade later.

I'm thinking of replacing a couple of the QVO SSDs with Ultrastars and using a couple of the FireCudas as cache drives for the platter drives. Good idea or bad idea? Would I be making a meaningful tradeoff or should I just go for the extra space?