Now we are cooking with dynamite! The VT-49 Decimator is big and angry. Let's take a look and how big and how angry it is:
VT-49 Decimator - 22 Points
First thought: That is pretty expensive for a single non-unique squadron. But let's look at the stat line: Speed 3, Hull 8, Anti-Squadron of 3 Black, and Anti-Ship of 3 Blue (no Bomber). That is pretty respectable all by itself. Add Rogue and Counter 1 and it just goes from good to great! You have a squadron that can do everything pretty well, and is hard to kill and get points from. Add on Heavy and it is almost a blessing, in that it disincentivises attacking the VT-49. Oh, remember how I was talking about parking Valen behind some YV-666s earlier? I changed my mind.
So overall a good way to invest in the squadron game, blow up some generics, and not lose your fairly expensive squadrons. Problems - it doesn't do much for Scatter elites, unless you can get some other shots on the target, and it is expensive to begin with. And Scatter elites tend to be less expensive than it is. On the plus side it does damage per point cost comparable to an A-Wing.
Morna Kee - 27 points
Loses Heavy. Adds a Brace. These are both good things. The best thing is that her special ability lets her spend her Brace to reroll any number of dice - and that just turns the expected damage of the ship from good to great!
Oh, and you can never get rid of that Brace token, because when she activates, she regains it.
For 5 points this upgrade just makes sense. If you have that 5 points you should always be running Morna before the generic version - it does what the generic does, but just does it better. It still has the same problems though - it isn't going to do much to a Scatter elite. But that isn't why you are taking it.