I would only recommend using the Breen shield against enemies using Polaron Weapons i.e. Breen.
(Breen shields give 30% defense bonus against polaron weapons)
Same thing with the Borg Shields. I would only use the Borg shields against an enemy using Plasma.
(Borg Shields give 15% defense bonus against plasma)
Aside form those bonuses, they're not great shields.
When fighting factions that use weapons other than plasma or polaron, I will use a high-cap covariant.
i.e. the Reman shield or the Aegis shield.
The Reman shield has the highest Cap of all shields that I've seen.
The Aegis shield has a slightly lower cap than the Reman, but has some additional helpful bonuses.
Also once you hit RA Upper Half, make sure to get the Blue MK XI Field Generator. This will add +35% to your total shield CAP, which can be huge, especially when using a covariant shield. I would call it easily the most useful console in the game.
I'm using Resilient Mk X [Capx3], with the covarient nerf I decided they were no longer *that* much better that the capacity out weighed the other bonuses available from different shield types. I found with a Covarient that even though I kept it up on my Fleet Escort with no trouble, if focused on I took a lot of bleed through damage, I can keep the Resilient up almost as well to the point where it's as near as makes no difference, but I'm taking far less bleed through damage now.
I've been using the Borg shield with the Aegis Deflector (I think it's the deflector; I use whichever Aegis component increases shield power) on my star cruiser for quite a while now and have found it to be phenomenal protection. I can handle quite a bit of damage over time and when the regen shield proc kicks in, I'm pretty much invulnerable* for the duration. That said, alpha strikes can be trouble, but with sci team and emergency power to shields, I can generally heal any alpha strike that significantly damages my shields.
*Invulnerability claim does not apply to crazy, impossible battles in which you are outnumbered 10 to 1.
Even if my math was a little off, being hit on one facing with TT running = roughly 1050 regen just for that facing, per second. IE: If Escort loses arc for 3 seconds, the facing will have regenerated 3150 HP - *Not* factoring in TSS, STeam, EP2S and/or Borg Procs
Ive literally seen my shields do the same yo-yo thing you often see on premade ships being focushealed. Drop to 0 on a facing, full mere seconds later, lose all shields to a CPB and full mere seconds later.
The only weakness of the setup is the lack of armors, but that is why I carry resist powers.