As a former owner of a supremely restored Bally Fireball, I have to agree with the sentiment that having a minty EM is so choice. If you have the means, I highly recommend playing one some day.
With that said, I am not a purist. I prefer games that play properly "for me". I like strong flippers that can make any shot. I like pop bumpers that snap a ball all over the place. I prefer buttery smooth drop targets. And I prefer inserts that do not act as a rest stop for the pinball.
I enjoy EMs that give me lots of sound. I like the bells to ring and the chimes to sing.
While Rat definitely defends the 3.5-3.9 degree rule, I personally enjoy the optimal pitch as defined "by me" for each game. Some games are optimal at 3.5 degrees. Others at 5 degrees. I do not care how an op in 1960 set his game. I was not alive and I did not play them then.
I'm playing them in 2015. And every game I own has a pitch that is different.
Just my 0.02.
Marcus