I did a large project with Wonderware MES 3.0 back in 2014. I only used the work order tracking part of the software and operator interfaces. This was in a large aerospace heat treating facility. As most others have, Wonderware bought a company that had a work order tracking system and then stuffed it into System Platform. I don't know how it is now but in version 3.0 the work order tracking part of the software was solid as a rock. SQL based proceedures that you could interface with very easily and well documented stored proceedures for you to use. The ActiveX object that Wonderware created were full of major bugs. I had been using Wonderware since version 2.0 back in the 1990's on Windows for Workgoups and have never required a hot fix from tech support. On this job it required 12 hot fixes! And it still had so many bugs that I had hundreds of lines of script to work around them. This was also the only job were the distributor actually gave us money back because we were so far over budget. Because of this I haven't sold a new Wonderware system since.
So my biggest recommendation would be to get the distributor/manufacture to give you some tech support and a guarantee that they will provide you with a product that actually does what they say it will. And if they refuse, find someone else.