Is there an "Enable All" option for up-sampling plugins?

Enabling upsample for plug-in enables it for every instance of the plug-in for all projects. It would not be a good idea to enable upsample on every installed plug-in.

gprokap
Ahh, so I only need to enable it once and it's enabled on ALL other instances of the plugin.

Yes
 

gprokap
Why would it NOT be a good idea with modern CPUs being as powerful as they are?

It is unnecessary in two cases:

1. for plug-ins which have build-in upsampling, although it might be handy if you only want to upsample on render
2. for plug-ins which do not benefit from upsampling.

 
It is undesirable when plug-ins do not tolerate upsampling. Upsampling can result in distorted sound or crash in some cases.

There was a thread a while ago where people reported which plug-ins benefited from upsampling. I noticed the SI series benefit from it, as does TH2 (the FX, not so much the amps themselves). But a lot depends on the sound you're using. 
 
Fortunately, you can do upsampling on playback to determine if you can hear a difference or not, and act accordingly.

Sanderxpander
Thanks. It would still be cool to have a list, perhaps this can be compiled over time.
SI series, you mean the Cakewalk Studio Instruments? Given the theory, I wonder why they would benefit? They don't process any external audio. 

But they create audio, and particularly the high strings from the SI Strings benefit from oversampling. 
 
I have to admit that as much as I love and use Kontakt, there was one song where I used SI Strings as a placeholder while I was writing, then switched over to some Kontakt strings for the mix...but the SI Strings worked with the song better. I never particularly liked the sound quality of SI Strings, but upsampling can make a big improvement with some of the sounds.