Engine trolley's rigid or steerable?

Newbie question really, but the majority of the static engines I see have trolleys with rigid axles. From a storage and space management perspective it would seem that a trolley with a steerable axle would make it more manouverable. Are there any mistakes to avoid if building with a pivoted axle? I was trying to avoid using a "wheelbarrow" arrangement .

Food for thought here...

https://ukengineforum.forumotion.com/t8559-trolley-for-villiers-mk15-wooden-toolbox-new-pics-5-9-2016#66184

Thanks Paul thats a good reference to work with

I have a mixture of both, I find the bigger the display the better it is with a steerable trolley otherwise you need to carry a steel bar for moving your fixed trolley exhibit.

Maryalice