Absolutely no doubt the Hoover was better, by a looong way.
I have used these Simpsons a few times, always thought the wash action was pathetic. Clothes on the top always stayed there, if overloaded (a favourite trick of mine, It's in the genes, just see my mother load a washer...) the clothes on top might not even get properly wet let alone clean. Hoovers spin faster too. If you saw them working side by side, the Hoover action is way stronger, even when overloaded it just powers through, the clothes get flung in and out with every turn of the spiral agi, with the Simpson the clothes underneath move OK but the ones on top barely move.
There is a clutch inside the transmission, it is a copper disc and a spring in the base of the trans, turn input shaft one way the shaft spirals up and releases the clutch (agitate action), turn the shaft the other way it spirals down and the clutch bites, releasing the brake which is between the pulley and the base plate, and turning the transmission, spin tube, tub and all. The pulley raises and lowers about half an inch as it changes actions, on wonky floors it can rub on the floor. This machine was in a very old house with a very wonky floor, vinyl underneath was badly scuffed so I raised the feet up to max to give more clearance.
The clutch is a weak point in these, and requires trans dis-assembly to fix so many "dead" ones need clutch replacement. Later ones have electric pump and neutral drain, so the clutch has an easier life and lasts longer.
I don't think the wash tub is any bigger, but the collar around the top including the lint filter is taller than the standard Simpson non-filter one, or that's how it looks to me.
Chris.