So I recently obtained an unruly amount of the mod, Suppress. This mod, as I am sure you are aware, reduces your secondary weapon's noise by 25% per rank up to 100%. For the sake of fun, I equipped it to my Dual Vastos as they are my "loudest" secondary weapon. To my delight they didn't reduce the actual amount of sound the weapon makes, just how far they alert enemies from. As I was power levelling my Nekros on survival I didn't get much of a chance to test their worth until now. I decided to play a mission I would have no chance with going in all-guns-blazing. I played a game of solo Ambulas assassination, as Loki (no sentinel). I found it quite astonishing, as I could turn invisible and unload an entire clip into an enemy and they wouldn't become alreted. More so, I could walk (stealthed) into a room full of enemies, and take out 2-3 of them before the 4th and final enemy became alerted. I ended up doing a perfect run: no detection, didn't get hit once (not even by Ambulas). Not only did the mission take significantly less time than expected, but it was an absolute breeze.
Despite how "useless" Suppress and Hush may seem, I believe they may give way to a new era of 100% stealth gameplay in Warframe.