Here's what I'd like to see done in Prime 4.
Mathcad convertor:
Don't flag minor font substitutions(or allow hiding the red bars). I don't care that the converter arbitrarily changed my plot from 'sec' to 'sec'.
On plots, move the scaling automatically to its new place in Prime. The converter knows that I want 'm/sec' but won't populate the new scaling box.
Provide some automation in Prime after I convert a file so I can select "ignore this warning/editoral" rather than having to manually change every instance.
Provide Post & Pre-Fix operator functions (/dB as an example everyone cites)
Provide subscript & and superscript formatting in text regions so that the converter doesn't leave me the job of looking for the substitutions.
Bring back the ability to convert from within Prime rather than having to do it externally.
Prime functionality
Bring back the ability to call Matlab functions from Mathcad. That's right, I don't want to spend my days writing functions in Mathcad that already exist in MatLab.
Provide the Trace functionality (track to data points) in plots.
Provide real axis, legends & titles on plots not text boxes that aren't attached to, and don't scale with the plot.
Support two y axes plots.
Allow real margins to be set not just narrow, normal or wide.
Provide subscript & and superscript formatting in text regions. No I don't want to embed a Math Region in a text box when I just want a X^2. At least PTC is consistent. I can't have text subscripts or superscripts even in the Discussion area.
How about access to date-time functions in worksheets so I can identify/label when I created or updated a graph or a calculation.
Bring back the print single width page function and/or allow printing of the scratch pad sheets that Mathcad user put on the right side.
The third party graphing converter proposed for MatCad Prime 4.0 (4th quarter of this year) is a very good start.