I’d do a X12SDV-4C-SP6F with 10x 20TB in a raidz2 with an optane slog, and still have room for 4 NVME to add later. Grab the 8 core for an additional $1K if you absolutely need it, but you’d be surprised what the 4 core can do. Low power, won’t make any noise with the right case, 10 year build. You only need to 4x your budget.

I’ve seen the same thing with Fast. I like that you can configure the number of streams, but sometimes you need to close all instances of your browser with them.