Having a couple of years of real life experience with ereaders and tablets, the lack of an expansion slot isn't a deal breaker. Yes, it's a nice to have and if there is a work-around that's comforting. I also know that everywhere I am likely to be, I have wifi access -- at home, at the airport, on vacation. So, the cloud thing to load up is absoultely, in my real life, good enough.
But, would I spring for the 16 GB as insurance? That's problematic because when you add in taxes and shipping, the "$199 Nexus 7" upgraded to 16 GB arrives at the door with a $312 price tag.