Being a Toro guy, I’ve sold both models and two things about those two units which I tell customers.  Unless you have limited storage space, I don’t see a reason for a SmartStow unit.  Second I like the 20065 with the Briggs engine.  That being said, if you can swing the price difference, I would recommend the model 21381.  The difference will pay for itself in the long run.  Better deck, drive, and with this unit I would recommend the Loncin engine, which is the same engine manufacturer as the engine on the model 20339.