It's a very tactical defense and only usefull for very experienced players imo. If you have the black pieces and you have no clue what to do you will be quickly overrun by white. I personally always avoid playing vs the pirc because i don't like the tactical style. The pirc defense is very effective against beginners because they have no clue what to do.. If you are a good tactical player this defense can be very intresting.
The Reti Opening takes a lot of patience to play.
1.Nfe d5
2.c4
If black takes the c4 pawn, then White will be able to take over more of the center and perhaps obtain the ideal pawn center. But if black advances in this position the game becomes the Reversed Benoni. And white will still be in a better postion.
But in most games black usually defends d5 with ...e6 or...c6. Where it would be best for white to castle kingside and advance his queenside pawns flanking black.