Being used to a truck camper, the 179 should feel like a castle. We camped next to some folks with a different model R-Pod last year and got the .50 tour. In their case, they has SO MUCH stuff crammed in that you couldn't tell what was what - sort of a mini-hoarding thing going on. The bathroom was a wet bath, which would be fine with us as we had that in our boat and didn't object at all. The kitchen space in the 179 is roomier than I would have expected and good counter space. I like the U-shaped dinette. One thing DH asked when he looked at the floorplan was if there was a place for a TV if you wanted one....didn't see one, but there could have been a mounting area for a flat screen.
Is part of your thinking the fuel economy? No info here, but you might check that as you still have the large frontal area, regardless of the sloping back.
Personal opinion is that there is definitely a niche for that type trailer and it may be perfect for your needs. I do like the look and coziness of them. Your tall son could be a problem, so would suggest a test "fit" before you sign on the dotted line.
If you haven't looked at something like the Casita or similar trailers, it would be good to do some comparison.
Good luck and happy shopping. Enjoy that trip next season!