So this is a look at the actual numbers that change with the Unique Upgrades (UU) and other upgrades, instead of -x% this and +y% that. I am NOT saying you have to use any particular upgrade. The idea is to look at each upgrade the slot the UU is in and give you the ability to compare numbers between them, so that you can decided whether to try the UU or another upgrade or not. Please go with what you think works best for you after looking at the various upgrades and comments. That said, if you like or dislike an upgrade, please say why as well. That way, people reading this thread and trying to decide if they want the Unique Upgrade or not, have something that gives an opinion on why a UU upgrade or other upgrade works for you or not. I will put my opinion at the end, but realize, my opinion is based on the numbers and not experiece playing with this upgrade, so take it with a large grain of salt. If you find any errors, please let me know and I will update the error appropriately.   NOTE: If you sell a Unique Upgrade, it is gone from your inventory and you can NOT buy it back. You have to open a support ticket like for a sold premium ship that you want back. So I HIGHLY recommend demount the module in case you change your mind. There are periodic demount sales and rarely free demounts for various events. Definitely do your homework on how the UU will change the stats on your ship as it costs 25 doubloons to demount a module.  
Minotaur Enhanced Smoke Generator mod slot 5 Unique (Legendary) Upgrade The Minotaur Unique Upgrade gives +150% smoke generation time, +10% max dispersion of shells fired at you, -5% detectability by sea, -15% duration of smoke puffs   Unique Upgrade in slot 5
22.5 second emission time, with slot 3 special Smoke Gen mod 1 you get 29.3s emission time 
96 second smoke puff duration, with slot 3 special Smoke Gen mod 1 you get 91.2s smoke puff duration
10.4 second rudder shift.  With slot 4 SGM2 you have 8.3 second rudder shift
9.6 km concealment with CE skill, camo & unique upgrade.
+10% maximum dispersion for shells fired at you
Assured detection of torpedoes varies by torpedo type.
DCP 5 seconds action time
Repair 20 seconds action time
Hydro 100 seconds action time
Smoke 15 seconds action time
RADAR 40 seconds action time
Concealment upgrade in slot 5
15 second emission time, with slot 3 special Smoke Gen mod 1 you get 17s emission time
113 second smoke puff duration, with slot 3 special Smoke Gen mod 1 you get 107.4s smoke puff duration
10.4 second rudder shift.  With slot 4 SGM2 you have 8.3 second rudder shift
9.1 km concealment with CE skill, camo & concealment upgrade.
+5% maximum dispersion for shells fired at you
Assured detection of torpedoes varies by torpedo type.
DCP 5 seconds action time
Repair 20 seconds action time
Hydro 100 seconds action time
Smoke 15 seconds action time
RADAR 40 seconds action time
Target Acquisition System mod 1 in slot 5
15 second emission time, with slot 3 special Smoke Gen mod 1 you get 17s emission time
113 second smoke puff duration, with slot 3 special Smoke Gen mod 1 you get 107.4s smoke puff duration
10.4 second rudder shift.  With slot 4 SGM2 you have 8.3 second rudder shift
10.1 km concealment with CE skill & camo.
Assured detection of torpedoes is 1.8km minimum.
DCP 5 seconds action time
Repair 20 seconds action time
Hydro 100 seconds action time
Smoke 15 seconds action time
RADAR 40 seconds action time   Steering Gears mod 3 in slot 5
15 second emission time, with slot 3 special Smoke Gen mod 1 you get 17s emission time
113 second smoke puff duration, with slot 3 special Smoke Gen mod 1 you get 107.4s smoke puff duration
6.2 second rudder shift.  With slot 4 SGM2 you have 5 second rudder shift
-80% steering gears repair time (I could not find the repair time in the Wiki)
10.1 km concealment with CE skill & camo.
Assured detection of torpedoes varies by torpedo type.
DCP 5 seconds action time
Repair 20 seconds action time
Hydro 100 seconds action time
Smoke 15 seconds action time
RADAR 40 seconds action time   Ship Consumables mod 1 in slot 5
15 second emission time, with slot 3 special Smoke Gen mod 1 you get 17s emission time
113 second smoke puff duration, with slot 3 special Smoke Gen mod 1 you get 107.4s smoke puff duration
10.4 second rudder shift.  With slot 4 SGM2 you have 8.3 second rudder shift
10.1 km concealment with CE skill & camo.
Assured detection of torpedoes is 1.8km minimum.
DCP 5.5 seconds action time
Repair 22 seconds action time
Hydro 110 seconds action time
Smoke 16.5 seconds action time
RADAR 44 seconds action time  
So by giving up 0.5km in stealth, you get 7.5 or more seconds of smoke gen for 17 less seconds per puff. You also get an extra +5% max dispersion of shells fired at you. If you like to sit in smoke outside of RADAR range, this just might be the mod for you. If you stack it with the special smoke mod you can almost double the emission time at the cost of 21.2s per puff.   
Master Thread link for ALL T-10 Unique (Legendary) Upgrades   EDIT Dec 19th, 2019 WG is moving the UUs to the Research Bureau for RB point. You have until Dec 31st, 2020 to complete any UU missions that you have. There will be compensation for unfinished grinds, but nothing on what that compensation will be.      Edit: In 8.0, Jan 2019, the CE skill changed to a flat -10% for any ship, so CE & Camo went from 9.8km to 10.1km, UU, CE & camo went from 9.3km to 9.6km,  and CE, CE module, & camo went from 8.9km to 9.1km.