Regarding CL, I think that depends a lot on where you live since most transactions are carried out in person. In my area there is typically very little quality DSLR gear on CL, but if you live near a major metropolitan area you may have better luck.
I mostly agree. But in the past year or so I have sold 100mm f2.8L's... 70-200mm f2.8L USM, 70-200mm f/4L USM, a 24-105mm f/4L, and then some entry level gear like a t3i, t4i, 60d, 55-250, 70-300mm, and a 75-300mm.
And I have seen other people selling a 70-200mm f/2.8L usm, a 5d mkii, a 580 exii, a 50D, a 430 exii, a t1i, a 60mm macro, a 17-55mm, a 70-200mm f/2.8L IS mkii, and some other stuff that doesn't immediately come to mind.
And I live in Central PA... which I would not consider to be a big city area.