I haven't watched anything from Jay, every time I watch something Linus makes it irritates me to no end how opinionated and flat out wrong he is most of the time. That's probably why everyone thinks SP120's are a good fan, he gave them such a glowing review but look at these:
Koolance fan compared to
SP120 Specs
Almost half the price almost and twice the performance.
Don't get me started on reviewers like him that advertise a freaking mod-right modding mat. Even he couldn't sell that like it made sense to buy it. His opinions come from his sponsors and own ignorance. And they really do not outweigh the sum total of the entire internet worth of reviews on different products and results.
That being said you did bring up a good point that we had missed which is different metals. Brass and copper are ok to mix, the plumbing in your house is likely all brass and copper. But you should not mix them with alluminum so that's another thing to check when you are picking out parts. The only way corrosion will happen is on parts that water touches, and I'm pretty sure nickel isn't used inside of any part. Plenty of things are nickel plated sure, but not on the inside where it counts.