I would respectfully suggest you check your bird's stats more carefully. I think it is likely it is the absence of a real testing ground that you are not seeing the bigger picture.
If Hardpoint is correct (and so far it has never been shown to be wrong--they're doing a good job), the stock Sabre has nominal EM signature of 2,876 with shields off (Highwayman mode--ready to jump a target). If you swap out the Panthers for Mantis, that drops to 1,332, or less than half the signature. That should matter if you are using your bird's stealth capabilities. Also, the Mantis should kill targets twice as fast as the Panthers, since part of their damage goes through the shields. Especially when you're fighting a ship with strong shields that refresh quickly, you really do want to be using ballistics.
If you then add the IonBurst, you're down to 1,045 EM sig, or almost 1/3 the standard. Improving the stealth capability means getting closer before opening fire on a target, and evading an opponent who is on your six much more quickly. These dynamics have been in game for a couple years now.
Additionally I would note that though the Shimmer shields are good, they are nowhere near the best in max shield or refresh rate. Depending upon your fighting style, you can hugely improve the shields.
Long story short, you can make an enormous difference in the combat capabilities of the Sabre, but you need to know where to look for those improvements. IMHO, flying the Sabre without concern for its stealth capabilities, is like shooting pool without thinking about where you leave the cue ball. You're only playing the first half of the game, but winners play the whole game. You absolutely need to know how far most opponents can be before they loose sight of you. That's what the Sabre's stealth capability is all about.
