It shouldn't be that bad. Nissan engines nowadays are known for their very good torque. If you look at their specs, they have lower horsepower than similar Toyota engines, but the torque is always higher.

In case you didn't know, torque is what gives you "pick up". Being a monocoque design, I think it should be as light as the Avanza. Or maybe just slightly heavier. If Avanza can move well with a 1.5, I'm sure a 1.6 Nissan engine will do fine.