the 352 is definitely tighter when all the slides are in. the Kitchen slide leaves about a foot between the counter and the dinette seat when all slides are in, conversely, the 350 is pretty much the same with front to back when the slides are all in.
But, when the 352 has all slides open, the space in the "living room" is huge.
What I have noticed is that small space does act as a "speedbump" for kids going from front to back
I have a 352 and Love it so far.