Hello @CaptainSavage_!
Thanks for your interest.
Your question is a pretty interesting one because MCE is really similar to GAS but it’s not using it.
I’d say GAS is an evolved but really harder to use version of what MCE offers. I’m actually thinking about reworking MCE for it to use GAS (in a distant future).
If you have the skills to learn and use the potential of GAS, I’d say you should learn it and build your own ability / stat system. MCE has some flaws regarding multiplayer advanced features such as movement prediction and multiplayer delay catch-up, flaws that GAS handles pretty well.
MCE is like a multiplayer game editor to prototype your game in a really short time. GAS is like a multiplayer game editor to ship a multiplayer game.
If you plan on shipping a game and you’re starting from scratch but with lots of programming background, GAS is your goal.
If you plan on doing learning projects or developing multiplayer prototypes, I’d say MCE is your goal. Of course, you can ship games with MCE, but it’s never going to be as clean as if GAS would have handle the multiplayer side of things.
I hope it answers your question. Feel free to quote me if it does not 
Have a great day everyone!
EDIT: MCE is like a complete system when GAS is like the pipes you use to build your system.
EDIT2: I also had question about MCE in on the marketplace page, questions that I can’t answer because they are part of the ‘legacy comments’. I’m going to answer them here:
Yes definitely, MCE should not get in the way of AWS.
What do you mean you ‘can’t’ find it? It’s contained within the game examples (or it should be). Tell me if you don’t find it there.
Also, 4.23 should be up soon 