I tought that SS had more required adjustement then EM.
We ran an old Playmatic for years in my parent's basement when I was young with no issues.
Of course, in that internetless day and age, once a part broke, we couldn't do anything to fix the flipper and ended up gutting/scraping it...
With internet, we still would have the machine.
anyway, I wouldn't say that EMs are unreliable.
Now, keep in mind that SS and EM are completely different types of gameplay, you might want to choose the game you like instead of wondering about reliability... it is useless to have a reliable machine that sees no action.