If it works, it works, but some of the newer "premium" synths and FX with Producer X3 are;
TruePianos
SI-Strings
Addictive Drums
Z3TA+ for modern synth sounds and "analog" stuff
The ProChannel Quad Curve EQ
The ProChannel Compressors
Breverb2 Sonar
TH2 Sonar (guitar ampsim)
Dimension Pro for random bread and butter sounds
Lounge Lizard Session for Rhodes
Nomad BlueTubes for a bunch of "coloring fx" (most of them simulate some tube warming)
Melodyne as a V-Vocal replacement - get the deal on the upgrade from Celemony, if you can afford it and do any kind of vocal repair.
Most of these are new since the X series, some of them since X3.