If I may chime in here, if Gig Performer is just sending program change messages to achieve preset+ or preset-, Gig Performer must be keeping track internally of what preset is currently selected.
This is tricky to do in midihub because you would need to store the value of the current preset somewhere. AFAIK Midihub does not offer variables.Plus, you would also need a way of initializing the value, getting the value of the first preset into Midihub somehow.
I think if your devices do not offer a Midi CC switch for these functions, you should probably give up on this.