Your shields die in combat pretty fast anyways simply because npcs starts to kill shields faster either ways after tier 1. The shield is an unique mission reward shield obtained only from completing a certain mission (no idea which one it is) and binds to you the moment you get it, that's why it's not to be found on the exchange.
To upgrade or not? If the next shield has better stats, then upgrade.
Or in your case just keep it and fly slow with the knowledge you got +5 more power spread around,
15 more to spread around. 5 weapon (that's about a 5% increase in energy weapon DPS, FYI), 5 shield, and 5 aux.
At a cost of speed, a stat I don't really care about in combat with my cruiser (usually at half impulse, during it, actually) or my science ship. My escort I'd probably use a Mk X engine if I PvP'd with him, but I'd still use this guy for PvE.
Covariants are pretty bad to begin with because of the terrible regeneration rate. Usually I stick with Normals or Resilients.
I don't know how you can make this statement at all. Currently, unless you are stacking regeneration items, you will not notice the regeneration rate affecting much in ship combat. Most of your ship repairs come from special abilities to boost them.
Some tests were done to show that up to 2 minutes of combat is needed for the regeneration to match the extra capacity when comparing resilient to covariant shields (depending on bonuses). I'm fairly positive these tests were done with blue shields, where the regen sheild had a double regen bonus, and the covariant shield had a double capacity bonus.
I know for a fact on my fleet escort that the double capacity bonus covariant shield array has more than trippled my shield effectiveness, where I can now kill things before the shields go offline.
Also, I agree that the engines from that quest are quite good. I've been known to use them on my ship at RA5, though recently I've been using some higher tier engines since I've been mostly impulsing my way through objectives.
if we're going to make this into a "which shield type is better" discussion its relevant to note that at higher tiers (4 and 5, pvp) shields will drop extremely quickly unless propped up with powers. any capacity difference less than 1k is hardly noticeable (maybe .5-1 second of reaction time if you're lucky). at that point you are better off going with standards; due to their balance they provide both higher amounts of reaction time (second highest) and regeneration (second highest).
I use a covariant on my crusier which is geared for tactical/support roles. When my shields fail (and let's be honest, i can run at 4 battleships and last for 3 minutes before they do), i can regenerate them reasonably quickly with an "emergency power to shields" call quite easily.