I love working on cradled wood panels. They are hard enough to take the pushing of collage without bending/warping, and once done, you can just put a wire on the back for hanging. No need for a frame: I love that!
At the Golden workshop we had earlier this year, the rep mentioned that wood panels need to be sealed before using to prevent the oils from the wood from migrating through the work over time….and she recommended Golden GAC 100 for that purpose. (apparently Gel Medium will also do the trick, but I found that out after I bought a bottle of GAC 100)