treadclimber - BIG load of crap if you ask me...there are treadmills that easily tilt farther than that, and you can run on them...and you don't have to walk with your feet a certain distance apart. There is nothing advantageous I see about a treadclimber.
And yes, treadmills are bad for your joints, thats a lot of impact on a really unforgiving surface. If it was padded, the belt would stick everytime you land, so there is no give. It's ok for sometimes, but, like someone else said, mix it in with some bike, some stepping, and definitly throw the eliptical in there, no impact there, and you can get your arms going too