Unless the VM's are given adequate harware I think you will stuggle.
You are much better off ensuring that your SEPM's and SQL are hardware based and located on the same GB lan segment.
Then use vmware SEPM for testing purposes or non critical roles. I use one dedicated to rapid release definitions and incident response.
I will be able to help you out with some more definitve hardware specs in a month or so as I have just started deploying into an environment with 300,000+ endpoints.
SEPM's are dual 3GHz Xeons with 16GB or ram. I am going to see how many clients I can get running off these before adding additional SEPM's.
I am not planning LU servers at this stage and will rely on 1000+ wildcard based GUP's at remote sites.
I am planning to run with very minimal logging and will do a lot of tuning.
Can't wait to see how it all ends up.
cheers
Z