Improvements needed to the DAX editor in SSAS Tabular

Many developers abandon SSAS Tabular (after their companies pay for enterprise licensing to get it) because of the development experience and they reason that if the development experience is poor that the product may be just as unreliable. The model designer has many problems and quirky behaviors when the model becomes complex (typically due to the number of tables & measures). In particular, the DAX editor can be very unwieldy. The auto-completion feature can cause more mistakes than it prevents. For example, if you were to backspace over a table and column, and then use the object list to select a different object; the editor makes a horrible mess by combing the old and new text. Some examples:
In trying to replace 'First Table'[First Column] with 'Second Table'[Second Column] the editor may produce:
'First Table'[First Co[Second Column]lumn] or ''Second Table'[Second Column]. Given the small font and text size in the editor, users miss the doubled-up single quotes.

When an error is reported, changes are lost; developers become angry & moody and are mean to people around them.

After making changes to an expression and pressing Enter to save changes, the editor shows the previous expression, causing the developer to think that changes were lost which makes them throw things and use bad words.

While you're at it, add support for comments and tabs.

I suggest a usability test be conducted and observed using a production-scale project.