Small size also poses a problem, the Ghadirs can't utilize a lot of the sound quieting systems used on larger subs in regards to it propulsion system.
Lets take an example we all know. Remember the Foxtrot, how noisy they were? The next generation submarine the Kilo was as quiet as its western equivalents but it was
twice the size of the Foxtrot with less weapons and a modest increase in sensors. Why the increase in size? A new drive system with many quieting measures.
On active the return from such a sub will be small but on passive she will be easier to detect. She can hide but she can't run.
I agree with you Sky that these subs are more for the use against tankers than warships. Unless a US warship sails very close to extreme shallows like the Cheonan did it would be safe. (The subs that reportedly sank the Cheonan was of the same class as the Iranian Ghadirs).
