Prior to releasing EirText for Mac v2.0 on the Mac App Store"), the app was sold via Paypal on my website. So far, the app has only been on sale for a week, but using the App Store as the sole method of distribution* has been the right decision in this particular case.
To give you a frame of reference, EirText for Mac v1.x was on sale for approximately 18 months. Prior to the App Store, I had to build my own licensing system and manage payments using Paypal**. This method worked fine for the most part, but there were times when codes would get lost in spam filters, or there would be issues with the user entering incorrect info on the license screen.
The downsides of switching from my own system are the usual App Store complaints - lack of control over updates, no trials, Apple's 30% cut, etc. As an iOS developer, I'm more than familiar with these issues, and while I would be happier without the restrictions, I believe the pros definitely outweigh the cons.
The Mac App Store removes the complexity of licensing and has boosted sales significantly. In one week, the app has already increased the EirText for Mac user-base by 85% (17% of which were gained on launch day). In another couple of days, more copies of v2.0 will have been sold than there are licenses for 1.x.
Crazy, huh?
* Technically, it's not the sole method of distribution, as legacy 1.x users receive the 2.x updates outside of the App Store.
** Of course, I didn't have to do this. But, EirText for Mac wasn't a high priority at the time and paying for a licensing system didn't make sense financially.