I have an old Pashley 20" Unicycle from the 80’s. Not ridden it for years but have just got back into it.
It’s OK but it’s very heavy and the seat is basic in design and in poor condition.
My question is will I improve my riding if I upgrade to a lighter Uni with a better seat? I’m interested in freestyle/trials.
A better seat will improve your crotch.
A lighter uni will improve your hopping.
Other than that the Pashley is probably fine.