The thing is that if I am using Readability already I wouldn't subscribe to Instapaper. Of course, readability may have paid back $1 from your $5 to Instapaper if you make the accounts from both to be synchronized.

Another thing is, since Readability's apps will be "powered by" Instapaper, Marco may make money from Readability subscriptions too. We of course don't know right now, but it is possible/likely.

The thing is, some features in the new Readability is exactly the same as Instapaper. This already sound odd enough for me. I just wonder why don't they get themselves under the same umbrella.