The main argument for a Chromebook over a tablet with a keyboard is web browsing (and by extension, productivity using web-based apps). No matter how powerful an Android tablet is, the browsing experience using any tablet browser is still going to be slower than a decent Chromebook. As you might be able to tell, I spend a bit of time on these forums (no duh

), and my device of choice to pound away at the questions is my Chromebook. If I were to use a tablet, the browser would be slower, and the Bluetooth keyboard would be less reliable (with occasional stutters or the inevitable temporary loss of connection). Sure, I could use the AC app, but that isn't as fully featured as the web interface.
Chrome OS has improved remarkably over the past couple of years (I can tell, since I tried a Samsung Chromebook briefly back then), and offline capabilities are much better. If you haven't completely committed to an Android tablet/keyboard solution, then I suggest you consider buying a Chromebook from some place with a decent return policy. Costco would be ideal, but Best Buy is also pretty good. Use it intensively for a couple of weeks, and if you find that the offline issues are still major concerns, then return it.