I am also a fan of a "boost" switch. We are all carrying around a huge house battery, so why add yet another? When I installed my second engine generator, I left my isolation switch in place solely for this purpose.
Most such setups don't have the wiring capacity to give a full jump-start with a totally dead battery, but usually a "boost" is all you need. Plus, with a little time you can use it to add a quick charge to a dead chassis battery.
But then again, with a Trik-L-Start and a bit of solar, a dead battery is not a common occurrence.
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now!: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)