This, so much. At a previous company, mixing manufacturers (not brands) was a policy: WD or Sandisk -> Hynix or Toshiba, etc.

Funny enough, this plays very well with RAID10: with each leg made of 2 different brands, a firmware failure will not affect you.

Which is the same advice given for disk-based RAID arrays. It is good advice and should be followed.

Just back sure they all use the same block size.

Sometimes that's a good idea, sometimes it might make things worse. A previous server that had a RAID-1 of SSDs was limited by SSD write speed. As the SSDs got old the write speed dropped significantly. If I had 2 servers that each had the same brand of SSDs then one server would need both SSDs replaced while if I had 2 servers with different brands then each server would need a single SSD replaced which would have been more hassle.

This is what lot numbers are for, the tracking (and in this case: leveraging) of variability between production runs. Spread multiple lots over more than one storage array and you're good to go.

Isn't this the same advice with HDDs?