For a brief time, I owned both the EM Mata Hari and the SS version in late 1980's or so. (Bought both from a route operator for $25 and picked them up from a barn). I thought the SS was a huge step forward and comparing the two insides side by side was VERY educational. I was always surprised they made both the EM and SS versions, and assumed it was mostly done as a proof-of-concept for them to gain internal support to make the switchover in their whole company. (I am guessing they had a team of mature electrical engineer hardware guys battling for popularity with the team of 'new kids' doing everything in software).

The EM I bought was nearly perfect. Just some contacts needed cleaning, the sequencer motor and flipper coils needed to be cleaned up and a few of the drop-targets needed to be fixed. Playfield was 8/10. Backglass was 9.5/10

The SS unit I got was a mess when I plugged it in before opening the backbox. It had the early MPU board, which had some battery leakage, so I cut my teeth and painstakenly learned how to repair a MPU board. Enough time and the RIGHT tools and it was pretty easy. And back then, getting the replacement parts was easy. Rebuilt the flippers, swapped some rubber and it worked perfect! I even came up with the clever idea to remote the battery back (got a replacement part at Radio Shack) before that was a thing! Powered right up. The backglass on the SS was another story. One of the colors flaked everywhere on the glass (the red or pink I think) and I tried to hand-paint the color back in with some stained glass paint and some white backer. (Apparently I am not the backglass repair guy!).

Anyway, I sold the EM and SS for $1000 a few years later (maybe 1990?) and thought I had made a ton of money!