We are using Cimplicity Open Process on a SCR pollution controls project at a 360MW and 720MW coal fired power plant. If proven satisfactory, we are considering it as a complete DCS replacement solution. As it stands right now, the main issue I have with it is that it lacks some database integration. It consists of an Open Process database and a Cimplicity database. We are told that it will be a totally integrated product(one database) by the end of the year.
I don't know anything about ProcessLogix so I can't compare the two.
We've just finished the automation of a Pulp&Paper Plant using Redundant Cimplicity Open Process. After some minor issues at the beginning, the system has worked really fine.