Model Flowsheet vs Process Flowsheet
There will always be different opinions on this, but I consider Model Flowsheets (or Model Section Diagrams) to be distinct from Process Flowsheet Drawings (or Process Flow Diagrams, PFDs, or other terminology).
While it is a nice idea to use the model diagram as the process diagram as well - I consider the freedom required to build really good models (with visual programming using generic unit operation models as required) is much more important.
I also like that when you look at a Metsim model diagram you can see what it does. There are no hidden unit operations, or models associated with an object someone (other than Proware) has drawn - there are no collapsed and encapsulated hidden graphical details. There may may of course be layers of control and user defined functions, but these are easily found as they are documented in the Output Reports for Controls etc.
If you find that you are repeatedly using the same combination of building blocks and functions to build a unit operation model that works well then maybe it is time to have that incorporated into Metsim - either for general use, or maybe just for use with your company's license key(s).