Viability of Voltage Controlled Amplifier circuit
Obviously you didn't build this, right?  This is a simulation?  Connecting the virtual ground of the opamp to GND is a no-no.  Your op amp will have no swing.  You either need to run both positive and negative supplies and define a ground in the middle or use voltage dividers all over the place to run the circuit off a single supply.  If you try to build this the opamp output will be clipped all to hell since it can't get below ground.  

The big problem with your circuit is that it is brutally non-linear in its gain programming characterisitic.  The current through T2 is exponentially related to CV, not linear.  If you want to connect your circuit to any kind of modular gear you're probably in a 1V/octave system or something.  Your CV range for this circuit is probably less than 100mV.