The problem with the statement there is that you posit the CT is the second worse place to put ammo, but we dont have any data for that. It sounds like most now agree that CT ammo is better then side torso ammo, so we are looking at head/arm/leg placement.
Full stop, I think head is everyone's favorite place. Much to my surprise, head ammo does NOT transfer in to the CT... its the only place on the mech. Further, you auto eject with ammo explosions, so in theory you survive the head ammo explosion with the pilot just fine. So yeah, in a land with no case, the head ammo exploding is still a perfectly salvageable mech. So in any example, the head is number 1 best location, but what is the second best location?
So side torsoss are worse then CT, but is the CT worse then the leg or arm? Well, the leg can be targeted, so it feels sketchy to me to put ammo in a leg as long as kicks are a thing. Arms are potentially more survivable then legs, as you can lose the arm from torso destruction so sometimes they never even go internal.
But with floating crits, the nice bonus to survivability the CT gets, and the extra damage to all other locations on top of random TACs, for sure makes it questionable to put ammo in the arms. Again, im assuming you arnt able to fully crit pad anything--if you could crit pad then there is no point to the OPs topic, as its about using the crit padding of the CT in the absence of crit padding elsewhere. So the arm would be 1 ammo and 4 arm actuators, and maybe like a medium laser.
Id rate Head, Arms, CT, Legs, Side Torso. With Floating crits, Id rate Head, CT, Arms, Legs, Side Torso. I think side torsos are worse then legs cause of the rear armor problem, and I think CT is better then Legs because kicks are such big deals in 3025.
Fully crit padding is always superior, no need to argue that... if you can fully crit pad something, well do that of course. But a partial crit pad, like 5 heat sinks and 2 ac bins on the hunchback H, is worse then the CT bins, so you need more padding then that to sway the monte carlo simulation.