Bathroom fans are not known for being especially quiet........
The issue with the units you speak of is that they do not have enough power to overcome any sort of static pressure.......
They have no real power - you could take the tip of your little finger and stop them from turning by lightly touching the blade, and you'd hardly notice the contact.
Now, your thin pipe is going to create static pressure on the air moving through it - and when that static pressure reaches the limit of the fan it will keep turning - but stop pushing any more air - and it isn't going to take a whole lot of pipe to reach the limits of those fans. They simply are not made for the purpose you wish to use them for.
Believe me - if they did work we would be using them all over the place. They are cheap and quiet......... what's not to like if they worked?