Very impressive project you have.
I am an electrical engineer and have been designing industrial controls for the power plant industry for the past 33 years. Over the years as technology advanced, the control system "life cycle" has become shorter. PLC's are good for 15 years before becoming obsolete, HMI's are good for 8 to 10 years before becoming obsolete and the software running the HMI's is even shorter. I'm not even addressing the cost of the PLC's, HMI's or the software. Fortunately your using much less expensive PLC's and HMI's compared to the Allen-Bradley and Modicon that I use.
I don't have any desire to automate my home brew system as I prefer the chef approach to brewing (taste, smell and adjust on the fly). I even prefer my tube amps over solid state for my stereo.
The important thing is that you enjoy your hobby/business.
Cheers