There's more to it than that, though I certainly can't disagree. I played a game last night that crashed and I had to reload. Well, I had gone through three consecutive ship designs called 'Def-Sm' ranging from 4 atk, 2 def to 8 atk, 12 def, and after I reloaded, they were all upgraded to the 8 atk, 12 def, and I've been playing it for quite some time without it CTDing.
However, that could explain why I often see CDTs on load, since I tend to overwrite the ship design with a new design of the same name (until we get something like CG1's military govenor).