I haven't had many problems with un-removable subs - aside from Devdas. But that particular disc was manufactured that way!
Although having said that I normally have the subs on when watching Hindi movies with my wife as she sometimes needs the subs to fully understand the movie. I
have had problems with subs getting stuck on one line of text for a long time (have to stop the film and re-start to get things working again). Have never seen this problem - but it could be becuase I don't have that many EROS DVDs!