How to change configuration of virtual machine from command line of VMWare ESXi host

The impact is greater than if you were running an older CPU with no support for EPT, but realistically the only way to determine if it's going to affect your workload is to actually profile the workload. Don't take the hypervisor out of the equation, because the whole point is to test the setup that you're running, not some hypothetical benchmark figure. Ignore Memtest86+, ignore bare-metal OSes, just find a virtual machine that's representative of a memory-intensive workload in your environment and beat the crap out of it.

Guy is dead-on: most consolidated workloads are bound by the amount of memory in the system and not by any other resource. By decreasing memory contention, the extra memory will probably help you out by enabling you to use more of your memory-intensive VMs' RAM as cache instead of it being ballooned out under pressure.

My preferred solution for this is to simply export them to an ovf or ova file using either the vSphere client or the command line ovftool.

In the vSphere Client, make sure the VM is off, then highlight it and go to File->Export->Export OVF Template. Then just follow the prompts.

Restoring is a piece of cake, just do the reverse (the menu option is "Deploy OVF template", I think).

To create a thin backup using ovftool

ovftool -dm=thin  vi://<user>@<esxi-host>/<vm-name> <local-file>.ovf

You may also wish to check out some of the options at http://www.virtuallyghetto.com/, I know these are very popular and I think there are some good choices for backups, although I haven't looked at any of them too recently.