Dissociation of benzoic acid
Solubility of benzoic acid(mw 122.12):


1.7 g/L (0 °C) - 0.00139 moles/100 ml
2.7 g/L (18 °C)
3.44 g/L (25 °C)
5.51 g/L (40 °C)
21.45 g/L (75 °C)
56.31 g/L (100 °C) - 0.04611 moles/100 ml


Solubility of sodium benzoate (mw 144.10):


62.69 g/100 mL (0 °C) - 0.4350 moles/100 ml
62.78 g/100 mL (15 °C)
62.87 g/100 mL (30 °C)
71.11 g/100 mL (100 °C) - 0.4935 moles/100 ml


So yes, sodium benzoate is more soluble than benzoic acid, but consider calcium benzoate which is less soluble. 

Calcium benzoate (mw 282.31):


2.32 g/100 mL (0 °C) - 0.00822 moles/100 ml
2.72 g/100 mL (20 °C)
8.7 g/100 mL (100 °C) - 0.03081 moles/100 ml


So the "real" answer is - it depends...