Discovery using iDrac or OMSA

Hello, 

I have the following setup:

5x PER710 with ESX 4.1 

5x PER720 with ESXi 4.1

I want to be able to manage these servers with OME to update as much as possible with the least effort (don't we all )

What is the best method of managing them with OME ?
What are the advantages/disadvantages of each method ? 

1. Should I use OMSA or iDRAC for discovery and update ?
2. Should I use the IP address of vSphere or iDrac for discovery
3. How should I configure the discovery options for each method?