Depends on the load and the line.. I think the NW2's are rated at more than 2amp max, but I've run one for hours with a light load (three bogie coaches, say 2 and a bit kg) on R1 curves, but no serious gradients, using both the Piko start set controller (28VA I think) and also a basic gaugemaster 00 unit, 12v only, 18VA (ie 1.5a max). The OO controller did limit absolute top speed, but the loco could still go fast enough to derail on R1's.
The gaugemaster lumps would be my choice, cheap and plentiful secondhand, self reseting current overload, and lifetime warranty IIRC. And you can nick one off the O/OO/N setup for half an hour to test the idea out first.
But, as I said, my NW2 was running a light load - if the newbie's line has meaningful gradients and long trains, 1.5amps might not be enough.
J.