Wolf Rentzsch ((Yes, I am late to reading this.)) on how to decide where to buy a particular app from, says:
Fortunately Apple now only accepts sandboxed Mac apps, clarifying the situation: customers should buy Mac apps directly unless there’s a good reason not to.
I disagree. Rentzsch makes some great points and arguments for buying apps directly, but there is a simple reason why most Mac users should buy only from the Mac App Store: peace of mind.
As Rentzsch lists, there are a few really strong reasons to buy from the Mac App Store — what he doesn’t say is that most of the reasons to buy direct don’t apply to the non-nerd population, which is most of the Mac user base.
Personally, being a nerd, iCloud alone is reason enough to only buy from the Mac App Store.