You bought the e-bike as a car replacement, so:
Load the carbon road bike with 50 lb groceries, ride the route. Since no rack, this would be in your backpack.
Load the ebike basket/pannier/trailer with 50 lb groceries, do the same. Which is better?
For pure pleasure riding for the fit, in a road race position, the e-bike is going to be no comparison. But that is not what you bought it for. You bought an electric grocery cart.
I was sick this week, fever & dizzy, but needed groceries. I pushed a 3 spd bike with rack bags lock and chain to the store three blocks away. This saved me from walking 6 blocks 3 times since you can't take purchases from one store into the other two stores. Voila, unpowered grocery cart. Bike had no utility as a bike since my balance was off this week. But beat dragging one of those wall-mart carts with the tiny wheels through the ditches, since there are no sidewalks here.
BTW, since stretching my range to 50 miles in 4 hours is the reason I bought a power wheel, no drag with a dead battery is important to me. AC socket is not available for charging at most festivals & concerts. The geared hub kit I bought, passes this test, since it has failed every time to run electrically over 13 miles. No drag, not noticeable. Direct drive "1000 W 48v" hub kit failed miserably. Drag was not too bad first 20 miles then something bound up internally and was like pedaling a dead whale with no cart. Never even got out to the country property where I keep the battery. Had to call for a ride back to town. No response from email to seller, thanks e-bay.