My guildies and I where discussing destinies, and how much it sucks to have to switch out of a good one to a bad one. It sucked being in shadow on my FVS.
I have seen multiple complaints on forums and people asking for a way to stay in main line while lvling other less interesting ED for that character. I know this has been talked in other threads but haven't seen a thread just dedicated to it, but my search-fu might just be weak.
My personal suggestion is if want to stay in main destiny then why not make us take a xp hit like 25-50% hit if want to put xp towards a different line while staying in main line.
That might not be very popular, but me personally would have a lot more fun and less burn if could play my character in it's main line and still advance in others.
Heres another link to a post in this thread from a guildie that is a great idea: