I would say it depends on the updates; are there actually conflicting updates (e.g. updates from both location for a NIC or something)? If HP is only offering driver updates, then you might be able to just bundle them into a new image. Take a look at this (Workaround 2) for an idea of what I am talking about: VMware KB: Upgrading to ESXi 5.x using Update Manager 5.x fails with the error: software or system configuration of …
Its better to use vmware image with hp customize driver integrate with image
Using HP servers, I believe it is imperative to use the hp download sources with supported (https://www.vmware.com/go/hcl) HP Servers. There have been numerous instances in the last 18 months where I am certain that having current updates to HP hardware (particularly Emulux deivers) has saved my bacon!
I have talked with a few admins with 10Gb Emulux NICs who went purple (purple screen) without the updates!
You can add the repository to VUM as indicated here: http://www.jonmunday.net/2013/03/19/update-manager-online-depot-for-hp-and-dell-extensions/
And then create a baseline for HP patches:
Or you can follow the command-line instructions I created here: Patch your ESXi Hosts from the command line easily and quickly - JohnBorhek.com
Thanks to everyone for their replies.
It seems that I don't need to worry, there *should* be intelligence in ESXi to only update drivers if they're newer, therefore duplicate packages should be a non-issue.