Are you asking me about my suggestion for 120mm fans?
Regardless, you're getting it! If you need 120mm fans for case fans then pressure doesn't really matter, you just want a solid fan with a good cfm/dba ratio. Also, several cases use fan brackets which require you to use 25mm fans. This is not a big deal. If your case allows the fans to screw into the case and there are no space limitations, then you can get a 38 mm fan. You can also mod your case to allow the fan to screw in rather than clip onto the fan bracket.
So anyways for case fans I think 25mm is fine because the extra pressure from the 38mm fans isn't really needed and it saves some room (i have an intake behind the hard drive tray and a 25mm fan is necessary.
Right now I have globe 120mm fans which are recommended by silent pc enthusiasts. These things are pretty dang silent at full speed and push about 67 cfm of air. 67 cfm is a good amount of air but you can do better. Now that I have them in the case, I can't hear them at all so perhaps a few more db's for a bunch of extra cfm is worth it.
I recently struggled upon this fan.
FAN
This fan is only 2 more db than the globe but pushes about 20 more cfm of air. That's pretty good IMO. The only problem when searching for fans is that difference companies measure their db ratings differently. For example, a fan may sound like 30 db from 20 feet away, but it's really 45 dba when you're next to it. The fan's that I have found to live up to their dba spec so far are the globe fans, panaflo's, sanyo's and acoustifan. Enermax advertises another adjustable fan but I have a hard time believing it's db rating so I'm not sure about the fan I listed above. it's db rating seems more sensible though, so I'd give it a shot. Also, It's important to note that I believe the above fan in the link is made by globe or globe and enermax are connected somehow. The blade shapes are identical and so are the labels. It was proven already by spcr that the globe and the acoustifan are the same.
Basically, I would go with that enermax fan above, and if you have room for a 38mm thick fan, a Panaflo M1a is a great fan (japanese versions are better I hear). That same site has the m1a for a good price with grills included. Oh, and if you can tolerate a little more noise (39 db) the Sanyo Denki's are really nice fans as well. If you can access the classifieds on this site you can get them for $5 each. If not, PM a mod about it.