Get the 4x5 - even if you never move up to the 4x5 size negative, you will be able to do bigger prints than you can with a 23C - also the lens is further away from the supports on a 45 so you have more room to move the easel around. No baseboard is not a problem, you can easily lay a piece of plywood on the supports and remove it for floor projections for really big prints if you want. It is a little wider than a 23, but not that much taller - and built like a tank.