There are other Pod devices that allow you to control Variax models from the device patch. The Pod XT Live and X3 Live/Pro also support this. The HD 500/Pro allow full control including using the JTV tone and vol knobs as controllers, as well as supporting the JTV Alt tunings, but the older devices mentioned above support model storage/recall within the patch. They are also cheaper since they will be used.

Furthermore, it will be a lot easier to reproduce your existing Pod Farm 2 tones with the X3 since the underlying modleing DSP is the same. In fact, you can transfer the tones directly between the X3 Live and Pod Farm using Gearbox. In some cases transferring tones from Pod Farm 2 to the X3 will not be identical due to some flexibility that Pod Farm 2 has that the X3 does not, but it will provide a good start, and it's a lot easier to dial in similar sounding tones in the X3 than in the HD500.

The HD500 tones are superior, and if you want to deal with the steeper learning curve the results will be worth it. But if you want the easiest path to keep your existing Pod Farm sounds and just add the JTV model control in your patch setup, the X3 Live is a better way to go. If/when you want better amp/FX tones (and the learning curve) then you could sell the X3 and get an HD500.