You could also check the fourdot fans on amazon, much cheaper and very good with more cfm and 3k rpm.
If you don't care about noise at all, then the fourdots might theoretically outperform the toughfans based on rpms. But even that is unlikely as there's more to it than just rpm/cfm like the blade design and static pressure.
^There you can see that the NF-A12x25s easily outperform fans with higher advertised rpm and cfm. And crucially they do that at much lower noise levels, therefore you can run them at full tilt 24/7.
So if noise is at all a constraint, I wouldn't pick the fourdot server fans. But otherwise, they're a great value.