Multi domain VS new child domain

Hi,

I need to create a new domain solution to support developer environments. Actually, the support of the actual domain (root domain) is managed externally from other company and they works very slow... the manager of developers needs to change that dependency to guarantee the fast deployment of new virtual machines (domain joined), creation of new users or groups andthe independent definition of GPO rules.

The identified requirements are:
- Maintain the atual Forest and Domain Functional Level (Windows Server 2008 R2)
- Independent / Autonomy management on the 2 domains (the atual company manage the root domain and other IT admins manage the new domain)
- “Domain admins” of the actual domain doesn’t have access to new domain or vice versa.
- Use the atual user login (atualdomain\user) to access the environment of the new domain.

The possibilities are:

- Creation of a new independent domain (newdomain) and  a trust relationship with atual domain.
- Creation of a new child domain in the atual forest.

I need to represent this 2 possibilities in 2 tables, like this example:

> Multi domain

Disadvantages   |Advantages
1 - a            |1 - a
2 - b            |2 - b
3 - ...            |3 - ...

> Child domain

Disadvantages   |Advantages
1 - a            |1 - a
2 - b            |2 - b
3 - ...      |3 - ...

Can you help me in that scenario?

Thanks.