Despite strangely subtle mention of the fact that the CEO and author are engaged, I think it's worth noting that has a material impact on a common sense analysis. In the likely event that this start-up fizzles out, it's reassuring that your spouse has a stable corporate job. Sure, engineers are in very high demand RIGHT NOW, but in a few years the bubble could burst and your family could be in trouble. Do you really want to put all your eggs in a single, very risky basket?
Great point. To sum it up briefly: we have no kids, no debt, and some savings. Now is the best opportunity to try and do this together. It's something we've talked about for a long time.
I'm pretty sure consulting work will still be there if the startup doesn't work out. I have SAP and Salesforce.com experience; both are widely implemented across the US.