Ok, some info;
The Castle ESCs are reliable ONCE YOU KNOW HOW TO SET THEM UP! That is key. I agree it is easy to blow them. But, that is if they are setup and programed incorrectly. I have gotten good at setting them up to survive.
The reason I am not using 4 motors is cost, complexity, packaging space, and weight. The differentials are $1,000 cheaper than adding two more motors. Oh, also, I have enough parts lying for two drive units, not four.
As for hub motors...... That is a great question. I never even considered it. I am so used to using my own reduction units that I never really considered anything else. On, one problem with using 4 hub motors is using 4 large hub motor controllers. That would take up far too much real estate on the deck. Not a bad idea, though.
1% of the world's population can think "Outside the box". The rest are firmly stuck within the box. Where are you?