We bought a used 24G this year (after owning an LTV Class B Sprinter), and we're happy with it after a five-week trip this summer.
Can't really help you on the 2017 model differences, and we have a sofa in the front slide (no evil cupholders:B) but I can give input on a few things.
We have a Lippert slide system and one of the two living room slide motors conked out soon after we got it. Don't know what brand they use now. It was annoying to have to take it into the shop, but it was a fast fix and the slides really make a huge positive difference for me.
We don't have the chair boosters. I use those front chairs as is every night and find them very comfortable (even after riding in it all day facing the other way). I just raise to the max height, and lower the arm rest if I need to lean on something to stand up. It's very fast and easy to swivel the seats, which was a concern I had, and it utilizes the front cab space as part of your living room. The ride up front is considerably more comfortable for driver and passenger than our 2006 Sprinter cab was.
Ours came with some nice options like full body paint - our previous van had decals. After 10 years on the road, all the van's decals were faded, worn and peeling. The Navion has been on the road since 2012 and the paint makes the RV look brand new. Can't tell you how long it will hold up, or whether it's worth $6K, but it really looks great IMHO.
Agree re the speakers. Never use them, never will.
We're really happy with the back queen bed, and sleep very well on it. I expected a hassle with folding down the top third, but it's not a big deal. Ours does not have a door to the bedroom (came with a heavy curtain we don't use.)
Like all the bathroom storage and we just did some mods to add extra shelves in tall spaces. We have a fixed sink.
We don't have/need a toad. Our old van which we loved was showing its age and was a little too tight after a big dog joined us. The amount of space inside now is a considerable difference, yet it's still quite nimble to drive and we're getting 15-16 mpg. We got a great trade-in on the van, and the 24G is has turned out to be winner for our needs. YMMV.