I don't find the C-PD overlaps with the firebird much unless you have one of the very flat, very stiff, very overstable PDs. It will feel like a firebird in the hand if you do. On the other hand, if you have one with a bit of dome to it, it can definitely take the place of an eagle or teebird. The bag setup I am using for worlds is:
KC Aviars (+1 super flippy PnA Aviar)
DX and KC Rocs
One Comet for turnovers/hyzerflips (in place of a cracked dx ontario roc
S-PD x4 (slightly flippy to stable)
P-PD (flippy)
C-PD (flat, slightly overstable and longer than a firebird)
CFR Glow Firebirds (super overstable, much shorter than the C-PD, longer for thumbers)
Star Wraith (Slightly flippy)
Destroyers x3
I am quite happy with it at the moment, especially considering I am really only using about 6 molds. (Wraith and destroyer are very similar.)
KC Aviars (+1 super flippy PnA Aviar)
DX and KC Rocs
One Comet for turnovers/hyzerflips (in place of a cracked dx ontario roc
S-PD x4 (slightly flippy to stable)
P-PD (flippy)
C-PD (flat, slightly overstable and longer than a firebird)
CFR Glow Firebirds (super overstable, much shorter than the C-PD, longer for thumbers)
Star Wraith (Slightly flippy)
Destroyers x3
I am quite happy with it at the moment, especially considering I am really only using about 6 molds. (Wraith and destroyer are very similar.)