Even though I am not in a production environment, I use FSP for all my vectorization, path editing, variable data (Autoserialization in the software), and adding contour cut lines to the jobs. I find the software to be extremely user friendly in these areas.
Any bitmap editing I still use PhotoShop... the features are just too good to pass up.
To answer your question on both FlexiSIGN-PRO and FlexiPRINT & CUT.... the differences are in the design features.
A few things FSP has that P&C doesn't... Autoserialize, Job Estimation Editor, Fan shape, Arrow shape, Templates, Convert to shape, Insert symbols (text)... to name few