python scripts and spatial head-difference observations

I would like to use spatial (vertical) head differences as an observation, but I am uncertain about the best way to go about this.  It seems that at least three approaches are available – PEST itself using the obs2obs.exe (and maybe more using PLPROC), an IFM plug-in, and a Python Script.  A Python script would probably be easiest for me to write,  but I am not sure whether it can be implemented or how it would be incorporated into the FEPEST's file structure.

So ..
1. Could you comment on any benefits of each of the three approaches?
2. Could you explain what can an IFM program can achieve that a Python script cannot (and any other relevant differences)?
3. If, indeed my goal could be achieved using a Python script, could you provide a workflow for developing such a script and how to get the other PEST batch, input and control files to recognize and run the script.
Thanks

Hi Stephen,

Actually FePEST does not use obs2obs.exe, since we have our own implementation. The easiest workflow is to connect the time series of head measurements to an existing observation point in the FEM file. Later in FePEST, you can create an Observation Definition, which depends on head differences (TIME1 - TIME2). By default the head differences are defined based on consecutive temporal records. HOWEVER, you can manipulate later the table, e.g. in Excel, and edit the time column (e.g. TIME - TIME INITIALS or anything else).

Cheers
Carlos