Nope, probably easier if you are carrying a heavy load because you'll have to run really high pressures in the 1.5" which will then ride rough. If you want tough with lower rolling resistance, then the 2.0" Mondials are probably the go to tyre, especially if you need to do light off road or heavy gravel because their better flexibility will give them better grip on uphills and downhills.
It's always a trade off, the maximum puncture resistance is with thick rubber under the tread, but this increases drag. Tyres like the Mondial use a thin high density fabric to do almost the same job.