Heintooga.
You said you have lumbar problems:

The reason most people love THICK airmattresses is that it allows your hips to sink in while laying in your side OR your back which allows your spine to remain straight side to side but to retain its "S" curvature fore and aft. I'm not a medical doctor but I think maybe you do not have a natural "S" in your spine, rather that you may be "flat" spined and therefore like the flat hard mats. <img src="/forums/images/graemlins/grin.gif" alt="" /> Or you may have one of those sideways "s" spines.

Anyway thats why most people love airmatt.resses
Jim <img src="/forums/images/graemlins/cool.gif" alt="" />