I would suggest you to read this article from Chris to get a better understandig of resource pools, because a miss configuration can have a huge impact.
http://wahlnetwork.com/2012/02/01/understanding-resource-pools-in-vmware-vsphere/
Also keep in mind that the whole share mechanism first applies if your esxi hosts are under contention (of course this does not apply to limits and reservations).
Regards,
Mario