The difficulty comes from getting used to Zen and going to the FS tables (speaking from PHOF on this point) or the other way around. They play very different, so it's difficult to get used to flipping back and forth. Personally, I'm in love with late 70's early 80's tables, so I have to get my Gorgar fix.
One small note on nudging: In PHOF you can nudge the ball so hard and so much that you can get the ball to the other side of the table... while this makes Gorgar a helluva lot easier, and Jive Time playable, on other tables it makes things too easy/unrealistic. While turning "Tilt" off is possible after beating the Wizard challenges, I found this pointless as you can nudge almost as often as you please anyhow. I prefer how Zen has it too where you can save yourself from a STDM, but not dramaticly alter the balls path.
While I'll likely buy every table available (from both) PBFX will always be tops in my house (no one else will play PHOF with me

) and I guarantee it gets far more play time overall.
..... and LOL and

on the Pinbot comment from SBViper, that's why as cool as Pionbot is I never put a quarter in a real one. Outlanes are MEANT to steal quarters in real pinball. Gorgar is a major fave, but the real table can take 2/3 of your balls in outlanes B4 U can EVEN USE A FLIPPER.... real tables so mean.