One thing I have discovered that EM's will always have over their digital counterparts is longevity and serviceability.

The earliest SS machines are now 40 years old. Sys11's are pushing into their 30's. Some of the IC's for these games are already obsolete and no longer available new. In other cases, substitute parts require modifications. I'm not talking about wholesale "upgrades / swaps" like replacement displays and more efficient power supplies... I'm talking about things like 6821 PIAs and other chips which aren't getting easier to find. Workarounds and/or expensive redesigns will become required at some point...

...Even then you'll always be at the mercy of a semiconductor plant with the specialized materials and clean room technology to manufacture arcane components with sufficient ROI.

Guys are already freaking out over Stern's Spike system which is only what, 3 years old? No info, SM components, limited availability. Good luck with those in 10/20 years. Even if the scematics and troubleshooting knowledge becomes available, it's all about parts. Nobody can make an IC in the basement. Even if you can break its functionality out into discrete components, that becomes a repackaging hack soup nightmare.

Whereas, with an EM... you can basically fix almost anything with a rock and some wire. Well, I oversimplify there but you get the idea. Even the most arcane one-off parts could be remade with common tools more readily accessible to the average hobbyist or supplier. There's something to be said for that!