IOS development is good for developing an iphone and ipad separately? Or is it good to develop a universal?

Recently due to work needs, due to short development cycle time

Need to develop a product to run on iphone and ipad platform

Advantages of a version

1. An installation package for easy management and distribution

2. You downloaded the iphone, if you have an ipad will automatically download

3. Pass the audit once, save time on line

Disadvantages of a version

1. The installation package will be very large, two sets of resources into an installation package

2. The various devices in the code are judged to cause code confusion (but this person is reduced)

3.ipad version of the experience will be relatively nearly (as long as the product is acceptable)

Benefits of two versions

1. Can be designed separately, after all, the ipad can do something that the iphone does not do (the experience will be much better)

2. The installation package will be small

3. Data layer/Logical layer sharing UI separate

Disadvantages of two versions

1. To separate management, distribution, need more manpower support

2. Audit needs to be separated

IOS development is good for developing an iphone and ipad separately? Or is it good to develop a universal?