I have the 356 Aft Cabin and my brother-in-law has the 350 Mariner. Choosing between the two seems to really be a matter of how you'll be using it. I will say that our boat feels a LOT bigger though it is the same length at the waterline. We chose the aft cabin for the reasons people mentioned above (2 berths and heads as well as the enclosed cockpit which is basically like having a sun porch (we have two wicker chairs and a wicker love seat on ours)). We also have and integrated staircase leading up to the helm so no ladder. My brother-in-law likes the Mariner because it's just he and his wife most of the time, and when they do have guests there is plenty of communal sleeping space. He also likes to fish a lot so he just got it rigged for fishing (can't do that with the aft cabin). We both have the big blocks, and I would definitely recommend them. I haven't really warmed to the looks of the Mariner, but that's just a subjective thing. If you do like how it looks, it's a great boat.