Welcome to the cnczone. You will find many ideas here and can explore all kinds of methods and materials to build your creation.
Don't take this comment seriously, but how many alterations can you make to reach the point that you can't claim that you are making a momus cnc?
The advantage or disadvantage of a design often boils down to specifications of some kind. Some has to do with rigidity, cost, difficulty in assembly or manufacturing, etc.
If you meet all your design goals then whatever you build is valid.
Structurally you want your design to be solid and stay in alignment. I don't know the structural specifics to comment on your proposed changes.
Often anecdotal info from other builders helps to answer some of your questions.
Have a great build and keep us informed.