I would wall mount only if I knew the wall didn't transmit any vibrations from elsewhere in the house to the enlarger. In my case my darkroom has a concrete floor so the regular basemounted setup worked the best. If your floor has lots of flex and vibrations (average wood floor) the wall mount may be more secure. In that case look for a good spot where the interior beams are close and solid. Near a corner is often like that. Giving the wall a good thump with the palm of your hand will usually let you know how much shake the section of wall has in it, just don't break any sheetrock! ;-)