It certainly is wise to compare free options to ones you pay for.
In my experience, the newspapers you pay for via Amazon.com are much more complete and better organized than via Calibre. Assuming you have the 3G model, web based solutions are more up-to-date than via Amazon.com, but there is that internet page load delay.
I have been reading the New York Times, for free, on mobile devices, for what seem like many years. Anyone remember AvantGo? Any day now, the Times is supposed to be putting up a pay wall. Then I'll get the 2 month free trial (sign up by Feb. 15) at amazon.com. And then, on or about tax day, the free gravy train they have been foolish enough to offer me, a former home delivery customer, will be over.
Or maybe they'll change their mind on the pay wall so that free access to the, IMHO, world's greatest newspaper will roll on
