Ironclads and Furiosos suggest you are wrong. Both of them were released with the same middling survivability, which has only decreased over time. The one thing Furiosos had going for them - 'exploding' wounds off of their Blood Talons - has been taken away, leaving the pair of them as average-but-not-as-good-as-other-stuff assault specialists who can't hold their own against characters, can't escape tarpits, can't really reliably defeat anything in assault actually, and are basically nowhere near as terrifying as they should be.Once they release a new model, we will see the switch
The only solid dreadnought is the Contemptor, and that's because it's tougher than leather, has a forcefield, and its Kheres assault cannon are superb. Give the Contemptor stats to the regular dreads but keep the weapon options as they are, give Contemptors AV14 on the front to make them mildly different apart from their weapon options, and I think you solve 90% of the Dreadnought's problems.