I only use a phantom center. That's the purpose of Stereo: listen to any classical concerto (violin or piano) through a normal 2-channel system, and the solo instrument will be center-stage, where it belongs.
The same thing happens with the L/R fronts in an HT setup — the dialogue will "seem" to be in the center, and sounds more realistic.
A phantom center eliminates the need for a center-speaker (saves money) and frees up an extra mono channel on your amp.