There are some really useful topics on SRM on the VMTN forum, for those interested in SRM be sure to check them out:
SRM bunch of questions
Some unanswered questions
How to backup and recover a recovery plan
I just love the VMTN forum! So if you’re still not signed up and participating be sure to join asap cause [...]

Check out this topic on the VMTN forum by Gabrie. It’s a good read about how many vm’s one would dare to run on an ESX host.
TexiWill:
This really depends. I know companies that are doing no more than a 10:1 or 20:1 compression, but there are other companies with 50+ VMs running on one box [...]