This sounds like an ideal application for a PLC and industrial controls rather than hobby grade equipment. Assuming the data is what is important I'd prefer sensors and controls that are calibrated and NIST traceable so that I'd never be called into question the validity of the data. Ladder logic programming is going to be easier for the next guy to adapt and troubleshoot because it is more widely understood by non-programmers who typically can support the hardware and unlike an arduino the program can be retreived from the controller if for some reason the original copy is misplaced or destroyed.
The downside would be cost, although inexpensive components can be found on Ebay or from discount distributors like AutomationDirect.com the initial capital expense is going to be higher, but I believe the long term costs will be equal or lower compared to using an arduino.