Mac App Store has one other advantage - it allows huge auditory to see and access your application. Without that you'll have hard time on advertising your application to customers.
Spending a lot of time on protecting your app from stealing also isn't a good idea - people who don't like to pay for apps will not buy it anyway.
I checked some not cheap successful apps, and they protect their apps just by creating file with somehow encoded trial start date - removing that file resets trial period. However, they have successful business.
Also, MAS protection is not ideal too, and apps from MAS can be copied to other computers after some tweaks.
Spending a lot of time on protecting your app from stealing also isn't a good idea - people who don't like to pay for apps will not buy it anyway.
I checked some not cheap successful apps, and they protect their apps just by creating file with somehow encoded trial start date - removing that file resets trial period. However, they have successful business.
Also, MAS protection is not ideal too, and apps from MAS can be copied to other computers after some tweaks.