1m or csl which is going to be the most forgiving on my back?

[Leche]

Love the csl and am considering buying one now that I have the funds, but I have a bad back, so I am considering a 1m as a softer alternative. Is this the way to go or is the csl not that bad? I will drive both before buying of course but just wanted an indication of ride quality.
Any advice greatly recieved.