The choice of sofa bed: buy with wheels can drag good, or folded good? The principle is to be firm, durable, and not easily damaged!
But as far as you describe, you choose a functional steel frame sofa bed, and choose a sturdy and durable sofa bed.
Wheels can drag and fold, and it's hard to judge their durability from this point of view.
There is a way for ordinary consumers a better understanding is to see the sofa bed of the same size weight, because it is a sofa bed frame + sponge + fabric + some other auxiliary, not what the high-tech stuff inside. The weight is heavy and the material inside is good enough, and of course it will be stronger and more durable. In Hangzhou, you can go to HOMMY in Gongshu to see FANTA. May meet your requirements.