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 Image may be NSFW.
Clik here to view.)

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?