Assumption 1. You only want to ever fire your ordnance when you have a high probability of rolling maximum hits (it's the only way they become somewhat efficient (for their cost)).
Assumption 2. Per Assumption 1, you want to only ever shoot ordnance when you have both rerolls and focus.
Assumption 3. Dumb firing ordnance is not usually practical due to the massive decrease in probability of achieving point 1.
I am only going to discuss dumb firing below since shooting ordnance with rerolls and focus already has a good probability of rolling max hits and this card does little to improve those odds (it does some, but the difference is not massive).
So this card seems to be the fix for the need for focus/TL but there is still not many missiles/torps I would be comfortable dumb firing (I.e. with only one of focus/TL). For everything else firing an ordnance shot with Focus/TL is usually enough to guarantee max hits (plasma torps, flechette, ion torps and assault missiles are notable exceptions since they need an external source of rerolls).
Currently a Concussion Missile with Focus/TL has a good chance to roll 4 hits anyway. With GC you can get away with just a TL, but you lose some flexibility, since any roll with 2 focus results and no blanks decreases your output.
The best place for GC is clearly Proton Torps, as it increases the flexibility as any combination of 2 hits, 2 focus, or 2 hits, 1 focus, 1 blank is good for max hits. More than 1 blank is bad news (unless you also have Guidance Computer).
Plasma and Flechette and Ion Torps have always sucked due to the difficulty of getting rerolls as well as focus. Both benefit from guidance chimps, but no enough to want me to dumb fire them, as you need to only have one non-hit result to achieve max hits. However these are all slightly more flexible if you can get focus/reroll shots from them.
Interesting note, that Proton Rockets do benefit quite well, and they do allow for dumb firing with just focus pretty well. You would need to roll 2 or more blanks to not get max hits, but of course that comes at the cost of Autothrusters.
So there is some increase in damage potential, but for many of them it doesn't help get to the magical max hits, and if it doesn't then shooting your one shot ordnance is typically not worth it.
But what about ships where it is useful?
Well the Z-95 is the obvious choice, but since they don't have access to proton torps (the most efficient when dumb fired) they have to use Concussions. Alternatively a dumb fired Homing Missile is ok, you would need to get 3 hits with your roll plus the TL reroll to guarantee max hits. The probability is not bad, so could be viable.
The Kihraxz suffers the same, though notably it is currently the best generic missile platform due to Glitterstim. It allows you to perhaps go for Assault Missiles instead of the traditional Concussion or Homing missile load outs. If it could take torps it would be better off.
A-wings have been discussed above, it is difficult to see opting for ordnance over auto thrusters. TIE Advanced Prototype suffers from the same.
B-wings (save Nera) probably shouldn't take ordnance, when they could take a cannon instead.
TIE advanced, actually becomes a viable procket carrier. They can be dumb fired wth just focus for a high probability of 4 or 5 hits. It is relatively cheap with only the opportunity cost of the TIE mkII (and points for the rocket).
For big base ships the opportunity cost of taking this (and ordnance) is pretty high, and seems not all that likely. I'll hold my breath on the Jumpmaster being and effective missile platform.
Y-wings seem well suited to the this card (Horton in particular), but ordnance Y's are largely overshadowed by TLTs, so we just won't see them.
TIE bombers/Punishers benefit from dumb firing Proton Torpedoes, and now they are a better option than concussions. The same probably holds true for the K-wing.
My big winners list (or ships I would consider using this on).
TIE bomber with Proton Torp, Extra Munitions, GC. 22pts.
A-Wing with Prockets and GC. 20pts.
Nera with Proton Torp. Extra Munitions, GC. 32pts (EPT to taste perhaps Crack Shot).
Ten Numb with Plasma Torp plus whatever you want.
TIE advanced with Prockets, one shot but a nice shot.
So it feels like this is still a pretty niche card. There aren't many things which are vastly improved with Proton torpedoes being an obvious exception. Most ordnance still doesn't benefit from being shot without both focus and rerolls, and when you have both GC doesn't add that much benefit (outside of massively low probability events, like rolling all blanks).