Last November I found out I was pg and not long after DH quit his job because he was so miserable and they really did treat him like dirt, similar situation where they would not let him advance as they said they would etc, and generally just pigs.
He;s never had trouble before getting work, he works in I.T so I said go for it.
Unfortunately I lost that baby but if I hadn't we would have been in the sh!t big time.
It took him 8 months to find another job, and not from lack of trying, like your DH he's a working man and was going nuts staying at home doing nothing and financially it hit us very hard, will be another six months before we fully get back on our feet.
If I had my time over again, and DH has said the same, he would not leave another job without securing a new one first.
IMO it's not worth the risk, unless your a millionaire, then I guess you wouldn't be working anyways