We have a 2017 24' S-series on order ourselves. Based on this forum and other websites, we went in thinking no deal unless we can negotiate 20% or more off MSRP (with our fingers crossed hoping to squeeze a few more % off if possible). We were willing to shop around until we got it.
We spent a lot of time at it (ALL FALL), but were able to take advantage of a great fall sale, the time of the year as sales slowed, and the fact we had another boat we were about to get at over 20% off at another dealership. These things contributed to us getting well above 20% off MSRP on a 2017 S-series at a great dealership near our cottage. There is fat to be trimmed, even on the s-series.
If you politely stick to your guns, and shop around, I am confident you can find the right deal in the right boat. Good luck with negotiations and your purchase!