Somewhat off topic but I hadn't heard of Instapaper before, have you used Pocket and if so what do you like better about Instapaper? Looks like they have a speed reading and kindle sync option which is pretty cool.
I use Instapaper. I haven't heard of Pocket. I like Instapaper's really minimal design, their "Instapaper Text" extension, and the ability to save and sort articles for later.
I personally like Pocket over Instapaper. It seems to work better for me.