YES... for the first few flights... you will probably bump into things...
its the difference between wasting $1000+ in your first few flights and not.
Just be cautious on very windy days., but to be honest if your not experienced, don't fly if its to windy.
I didn't find they acted like sails as some say... I did find they saved my quad when I bumped into plants and stuff when I first got it.
VRS shouldn't be an issue now considering how slow the Phantoms descend... but yeah, if you have no experience flying I highly recommend you get them.
Just becareful you do not mix up the screws, its been mentioned already, but using the screws to mount the guards when you are not using the guards will kill your motors, so just pay attention and make sure you put the correct screws back in when you take the guards off..
BTW My info is related to everything except the P3... I have no idea about that quad...