Yes and no I guess. Sure, with an open stack you are more flexible, but it also means you have a LOT more infrastructure to build to begin with**, which in our case of a two-man band would mean months of work or not even being able to pull it of at all. So instead of we consciously decided to focus on perhaps a more limited group of people we can deliver a polished and awesome service, knowing we can’t service everybody, as opposed to having to spend a lot of time on infrastructure or being forced to build a much larger team.
In case you’re interested, I talked more on this topic here, explaining the trade offs and the choices we made: The Next Box™ – The story of how Agenda came about - #8 by mekentosj
**) unless you go with some other companies solutions, which brings you back to square one, and at least we know iCloud won’t go away overnight as some other service tend to get deprecated out of the blue. Second, not only build but also maintain a lot more infrastructure. We literally never have to worry about the cloud infrastructure at all, Apple takes care of literally everything, including costs not unimportantly.