Welcome to the family.
I am a long time user of GP and I am glad to help you.
You should think about creating different rackspaces with the plugins you need and switch them.
When you just build a multitimbral rackspace (similar to a multi for example on a Motif etc) there is a chance that you get hanging notes when you switch the channel, because the needed Note Off message on the old channel will not be sent.
Consider to create a rackspace with all sounds and splits you need for a song or song part.
And build another rackspace with sounds needed in others songs or song parts.
And not to forget: With variations you can use the same plugin and change for example cutoff by using so called widgets.
So you can build a rackspace with 2 variations, create 2 widgets which can be mapped to cutoff and resonance in bx_oberhausen.
Then in the 1st variation you can set the widgets to value you want and do the same in the 2nd variation.
This way you can switch between 2 total different sounds whithout any hanging notes or glitches etc.
With variations you have so many possibilities to influence the sound in realtime you would not have when just switching a Midi Channel.
Switching a rackspace (or better variation) is possible when you send PC messages.
Each rackspace variation can have its own unique PC number.
Or you can assign a Midi Controller in the global settings to switch to the next Song or Song Part or rackspace variation or switch back.
In SetList Mode you can assign discrete CC Messages to Song Parts.
This way when you have for example a foot controller with 4 Buttons, you can directly switch to a Song Parts by pressing the corresponding button on you hardware controller.
In my bands I am using backing tracks from Ableton Live.
With the usage of OSC Messages I control Ableton Live completely.
When I switch to the desired rackspace the corresponding Live Scene is selected.
When I press play in Gig Performer the selected Live Scene is started and when I press play in Gig Performer again it is stopped.
This way I can use scripting to switch automatically my racksaces / Songs /Song Parts and I can concentrate on playing without to think about to select the correct sound!
Endless possibilities: But this is only possible because I do not use Gig Performer like a Multitimbral expander and switch sounds by selecting the correct MIDI Channel.
I can help you if you want and build an example rackspace with PA plugins, if you want.
Just call me, and I and all others here in the forum will help you.