I'd recommend the DreamTime sleeping pad. It's another inch thicker which would be more beneficial for his back issues. I've never had a Therm-a-Rest leak air in many years of usage & my older ones work even better now since I've replaced the metal valves with plastic ones.

Based on Cascade Designs excellent durability, you will not see air leaking out of this pad over the life of the pad! One of the things Cascade Designs does with every single pad before it leaves the factory is fill it up with air near it's bursting threshold using an air compressor and leaves it for 48 hours on a padded shelf. Over the course of these two days, it is monitored by several people using calipers to make sure it's thickness remains the same. If it passes this last QC test, it is then packed and made ready to ship. No other company takes this drastic step to make sure each pad holds air before leaving the factory. You won't have any problems with air leaking out, unless you're careless with it. Make sure that nothing pointy and/or sharp is underneath it before laying it down. lf you do this, it will last for decades.