It's not hard to follow, but it makes you think and you'll often be rewinding just to really understand what a character was saying/meant. It's beautiful. ^^
....Gash? o.O Yes, I'd be extremely confused too. If that happened, I would have to go back and watch the whole sub over again just to get comfortable with the changes.
Oh no, I would heavily dislike that! I don't mind dubs or subs, but I mind if it's not consistent. If all of a sudden, everyone's got a different voice and is speaking another language, I'd be very irked!