Just as you mentioned a number of VSTs in Mixcraft are not available outside of it. As for the other VSTs you have trouble loading in GP, are they 64 bit or 32 bit? GP just like any other VST hosts these days loads only 64 bit. VSTHOST a free VST Host has a built-in bridge that helps import both 32 bit and 64 bit plug-ins. However, the host is just too limited in comparison with GP. I use jBridge to load a particular, discontinued 32 bit VST into GP. Then again, all other VSTs of mine are 64 bit, and I have no trouble loading them in GP.
Gig Performer, aptly named, is dedicated to one thing; make personal instrument setups out of one's collection of VSTs and play them live. It is so flexible and easy to use. It was very easy to make drawbars for organs from scratch and slide up and down right on my hybrid touch screen. You can make just about any kind of customized control. Programming your own setup in it is actually fun. With other apps, it's a big chore.
One of the many neat features of GP that I like is patch persist just like Roland's patch remain.
https://www.youtube.com/watch?v=y8t8p7JVy-0MC doesn't do that. Maybe it's not even fair to compare GP with any DAW, as no DAW works like GP, and GP is a VHT host for live performance not a DAW.
I downloaded a demo Gig performer..
I had a problem with the program reading my VST plugins... same folders that every other program was able to read..
I isolated a folder from MixCraft and selected VST's that came with MC...
Most would not load in Gig Performer... since they are Proprietary.
I am not willing to give up the VST's in MC.... and I found MC to work better...
Also MC has combination VST map that allows unlimited layers and splits.. This feature made Forte not necessary..
Sorry I am convinced MixCraft does the job for me..
I will play around with Gig Performer a bit more {see if I can make head way}.... before I delete it..