Yes, the Thudbuster was my first idea as well and I bought one a few months ago in hope that my back will not get as badly abused.
The Thudbuster did help but is in NO way comparable to a rear suspension.
It feels like the bike comes "bolting" up and only 2-3 inches away from he spine dampened 30-40% where a rear suspension IMO takes at least 80% of the impact.