A:Answer The 27" model can side vented without punch outs AND backed right up to the wall, because it's designed with enough room for the vent to go to the side, in the area between the washer and dryer.
I've been going nuts with the exact same question. They don't make it easy! I think is so you'll hire a handyman/ private installer to do all unusual venting, but that is not needed in with this model. From my research and studying of the installation manual, the 24" smaller unit needs a punch out, but this one doesn't. The area connecting the top and bottom (dryer and washer) is designed to make it work with no punch out. You can back the unit right up to the wall. It says you're supposed to have 1" clearance in front if the unit, but 0" behind. So the Plug- and Play installers from Best Buy should be able to do it - if you have the correct long enough rigid metal vent tube... (I suspect 15" but don't quote me), which needs to be UL rated.
The installation manual makes it sound like there's a built-in elbow at the vent point on the unit - and that can be rotated to point left, right or down. The straight tube gets attached to that till it extends past the body of the unit, where the overheating/ fire danger is less. It can then attach to a flexible aluminum vent or whatever you've got. Search the internet for "GE Model GUD27ESSMWW Installation manual"