Our use was for running single application, Data acquisition and control systems, so IT managers were not an issue
We used a few versions of OS/2 up to and including Warp.
From 1995 onwards we started to migrate to NT and were fully on NT for Client - Server configurations by the end of 96, when NT 4 was more generally available The SCADA systems used a lot of dedicated I/O and the HAL suited this way of working.
We were so at the cutting edge at that time we used to get the System engineers for the SCADA developers ringing us
up for help with systems they'd sold to our competitors
We never led them astray of course
although it did mean that we could get the software developers to fly out to site to solve issues themselves, that certainly impressed the client