I sleep on an 'ultra firm' mattress but every now and then I get the urge to spend a night on a hard surface setup similar (though a little thinner with the pad

I sleep on an 'ultra firm' mattress but every now and then I get the urge to spend a night on a hard surface setup similar (though a little thinner with the padding) to yours. No idea if it's good, bad or neutral for my back health overall. Doesn't seem to be hurting and I've no history or experience of back pain, but like you say, single data point here too.