Yes, they are well worth it. Once you buy the decoys....get a 4 or six slot bag.
When you said a couple....did you mean a couple of doz or just a couple of decoys?
BigFoot also makes a great decoy....but doesn't produce shells.
FA, DZ's and DSD...are all great decoys but all require some sort of TLC.
BF/s don't...unless you want to protect the newer flocked heads.
Both shells and full bodies have their place....and can be used in many different situations.
Needless to say, you can get more shells into the field...easier, cheaper, and in some cases faster.
Step back....take a look at your hunting situations would most require...and at the least possible inconvience to you.....and your buds.
I hope this helps somewhat.