Yeah, I'd stick with coil springs. Less risk of failure, less risk of consequences of any failure. If I still weighed north of 200 lbs I might trust a U-spring made from flat steel stock, although it would be heavier. I'm down to 150 lbs now so that
Rinsten spring might hold up okay.

The ride will be bouncy and pedaling less efficient. But sometimes that's a fair trade off for comfort. My first bike when I resumed cycling in 2015 was a comfort hybrid with thickly padded saddle with coil springs. I needed it to gradually improve my fitness while recovering from neck and back injuries.

And my main hybrid has a thickly padded saddle without springs. It still feels very bouncy compared with my road bikes with minimalist rigid saddles. But it's still very comfortable for casual rides when I'm not looking for a workout.