Over the years, we’ve found that even power users who know they’ll eventually go into SQL mode prefer to start in the visual mode, as the grouping, date formatting, and joins are all done automatically.
Right now the SQL we write is very proper - with quotes around all of the column names and table names listed before each column name. It's not what a human would write. I'd love to one day make it a little more human so that the switching into SQL mode will feel even better. It'll be a fun project.
One issue I've had with pure SQL for analytic purposes is that a user can't build a library of higher-order functions that can be parameterized (imagine a window function to do a cumulative returns across various time periods, applied to different underlying source columns), so its difficult to build up a common business domain language without taking the typical approach of constructing SQL through glueing string fragments together typical of most programming language SQL libraries.