Yeah from the little you can find on the internet the 2017 CX isn't the same as the 2016 CXM, looks like they just added DC-DC converters to the old CX
I'm with Chugalug here. A SSD is nice but easily upgradable when you can get the cash. A 1600 will be good for many years, a 1400 probably won't.
If you partition your HDD in a size of your to-be-SSD, you can just clone it on the SSD when you get one.