For at least year Instapaper wasn't really moving forward. Design feels outdated, the website looks like thrash. Pocket on the other hand looks and feels pretty awsome. As you can the fact you paid for the app or not has nothing to do with this outcome so far.

Instapaper situation is the best example, that Marco's jabber that you should pay for apps if you wan't them to last is just plain wrong. The free vs paid doesn't really matter in long run. Fortunatlley you can switch from one to another within a week, so its not much of an investment anyway.