bitflipper
Switching patches isn't something you'd want to do mid-song. Depending on settings and the patch, it can take (up to) a couple minutes, so I have to plan ahead. Depending on the gig, I may only use one patch. I use only a handful of patches anyway, which I've gathered in the User folder so at least I'm not wasting time scrolling through them. 

One of the big advantages to using Omni2 is the LIVE mode. You can preload up to 8 instruments and switch between them with a mouse click (or touchscreen).
 
https://support.spectrasonics.net/manual/Omnisphere/live_mode/index.html
 
Regards,
Dan

If you have enough RAM, anyway. In live mode, Omnisphere fully loads all the patches in your multi into RAM, and that's why you can quickly switch from one to another. If you have only 8 GB as I do, you're still severely limited as to how many patches can be loaded at once.
 
Furthermore, if you fully load a Keyscape patch (turning streaming off) it can be HUGE and may not even be loadable. The C7 normally takes up 3 GB, but that's just the preload buffers. The whole thing is actually 44 GB!