iPhone/iPad Project Upgrade and Universal vs different Device specific projects

According to the topic Using a Single Xcode Project to Build Two Applications, I should choose to 'Upgrade' the iPhone project to include an iPad. However, the page does not discuss pros/cons of Universal versus Two Device Targets.

I think the most desirable benefit of开发者_运维问答 an upgrade is the 'single source' - write once run everywhere (unlike Java and its 'debug everywhere').

I would like to know the problems encountered in the field when using universal binaries versus distinct targets?

The most common reason to avoid building it as a universal app is if you want to charge more for the iPad version. A universal app has a single App Store entry. Building it as two separate apps lets you submit it twice, and set different prices for them.

The single/double App Store entry issue has a lot of ramifications - merged/separate reviews and ratings, release charts, promo codes, etc. They are essentially different apps from the App Store and end-user point of view.

I'm not sure what you are getting at with the "single source" point. Just because you are generating two app bundles, it doesn't mean you've got two copies of the source code.