Performer Trikes is offering a new model with a heavier load capacity and a higher seat than their other models. It is named Hero. It looks to have 20 inch wheels upfront and a 700 rear wheel. 18 speeds will cost 2,200 USD and the 22 speeds version 2,450 USD. You can read about it here:
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Tadpole Rider 
At that price, The Performer Hero model should come with an electric assist….