I also like the idea of the MDI. For very little money I was able to add a gateway and send all my engine data to my NMEA backbone. This allows me to access engine data on my sailing instruments and MFD, much handier than the dedicated engine display at foot level in the cockpit.
The issue is...
Although Volvo D1 and D2 engines are mechanicle, they have a MDI (mechanical to digital interface). This little black box not only translates engine data and alarms to Volvo's version of NMEA2000, it also handles the stop and start functions. When it fails (not if) you can not start the engine...