What is the maximum number of data points that Dips can handle?

The number of entries in the grid isn’t restricted at all.  In practice it will run into performance considerations drawing too many entries on the screen and will eventually run out of memory.  However, it won`t generate “All Intersections” for anything above 4000 entries in the grid, as the number of intersections increases exponentially; everything else will still work, though.  

Note that the quantity column in the grid can be used to consolidate multiple entries with the same orientation.