Collossus MK.III has a Converted Cargo bay hullmod (the only one to have this mod), in which fighter speed is reduced by 17% and damage taken is increased by 25%.
Survivability for Carriers is their speed and Collossus MK III speed (50) is slower than Drover (75) and Heron (80). It is faster than the Condor (40). It's also significantly larger than any destroyer. Of course, if your carriers are never in a position to get shot at that doesn't matter, but that's a poor assumption to make. If you are happy with the Condor, you would be happy with the Collossus MK III.
Drover and Heron is better, but at least it isn't a total waste of supplies and fuel to recover it since fighters are useful. I suppose in theory, you can try to make it into a combat carrier with a pair of light mortars and light dual autocannon, but you will probably have to remove militarized subsystem, by which time if you don't care about your sensor profile, you would probably have better options.