That document is quite interesting—thanks for sharing it! I wasn’t aware of the dates at which various products were being discontinued.
These systems were popular for large applications in my area; their popularity persisted well into the 2000s, as most MXLs I see feature the Siemens logo and the larger display. Siemens seems to be persuading its customers to upgrade, however, as three MXLs near my house have been replaced with Cerberus Pro Modulars since 2020 (coinciding with the discontinuation date for the detectors). SSDs mounted in RCC cabinets, as pictured below, are becoming a common sight around here:
Despite their reputation as having certain peculiarities, as you mentioned, I’ve always thought they were interesting systems from an enthusiast’s perspective as they were seemingly capable of handling almost any application (and the large blueish display paired with a black cabinet just looks so cool to me!). If the MXL lasted as long as it did, Siemens and its predecessors must have done something right.