I think the question should have been, "Are escorts value for money??"
I would answer, "It depend what you buy."
An attacker doesn't have to engage an escort(s), he can just elude the escort(s) and end up between the escort(s) and the prey. For the defending player to have this happen is negligence.
I've been in SFB games in the past and have been pretty good at luring the ecsorts away to allow someone else could attack the prey. It's all about psycholgy and a millitary term called "going impetuous".
For example a Federation convoy of 3 x FTL and 1 x AuxCV is escorted by lone Hunt Class light cruiser. All the Fed players are inexperienced but keen.
The Klingon attackers have 2 x K-F4B and 1 x K-F5S which is providing search and aquire for the squadron. (An K-F4 is the frigate version of the K-E4 for those who don't have SFB!! THe E4/F4 is smaller than the F5, which has a roof shaped, triangular secondary hull.)
The Klingon players are veterans.
OK the pair of K-E4s move in towards the convoy whilst the F5S keeps its distance, shadowing the convoy.
The Fed CL player, realising that he more than outclasses the K-F4s moves out to engage the "easy kills" whilst the AuxCV player decides to stay with the 3 x FTLs for now.
The K-F4s exchange shots with the CL and turn tail and head away. The CL chases them, not wanting to let the frigates to escape. He is more interested in chalking up two kills now than the convoy. This is called, "Going Impetus" in millitary parlance and has lost battles throughout history (and sometimes won them rarely.)
The AuxCV player decides that he wants a piece of this action and moves away from the convoy to backup the CL.
Remember the F5S scout??
He waits until the the Fed ships are a good distance from the 3 x F-FTS and then moves in for the kill of the helpless prey.
The CL and Aux CV players break off the pursuit of the K-F4s and attempt to rescue the convoy. At this point the K-F4s can either now turn and harrass the escorts or escape. The escorts do out match them. They need to buy the F5s enough time to waste the 3 x FTS and possibly assist an escape for it as well.
If everything goes wll for the Klingons, all 3 x FTS are mullahed and the Klingons leave the map with a few scratches.
The Klingons would win this hypothetical game as they played as a team with a team plan that they stuck to. The naval tactic is a very, very old tactic and was the main tactic used by the English Navy against the Spanish Armarda. Also a standard MTB tactic in WW2 in both the Mediteranean and te Pacific campaigns. It's even older that "Crossing the T"!!
An experienced Fed team would not have fallen for it and kept it tight. And if you've understood this, neither will you.
The AI will fall for this every time in the convoy attack.