I do not agree on you with this statement that you made. Commando and merc are a mirrored subclass so they are basically the exact same except for names, armor look, different animations. So there is no way a "Merc is worse than a commando" or "Commando is worse than a merc" They are the same attack wise and both have the same escape issues.
You are incorrect. The advantage that the Commando has is that he is not hindered by the presence of the offhand weapon. The offhand weapon natively has low accuracy which combined with the mutli-attack resolution of the Merc's abilities, virtually guarantees at least one miss when attacking an enemy target. Why is that important? Because of Retaliation/Riposte. It means that when the Merc uses RapidShots vs. an attacking enemy melee, he is causing more damage to himself (the Merc) than he is to the enemy melee. That is retarded.
In order to somewhat ameliorate this negative effect, Mercs need to stack more accuracy than do Commandos, who can stack more Power. This is why the Commando is slightly superior to the Merc. By way of comparison, the dual wielding Repub class that has a single wielding mirrored Imp class (Gunslinger vs. Sniper), specifically has an ability that allows him to increase accuracy by 30% for just those situations.