A gotcha that hits me here is that, by using a pressure tank, you will likely run into a cleaning/humidity problem. You need that air to be flawlessly clean and the act of pressurizing and depressurizing the tank would make that difficult. Additionally, you need to pressurize near-boiling water as well so you'll need a boiler/water mixing tank. Finally, the temperature of the actual brewing environment is important, otherwise the outer edges will be lesser extracted.

On the other hand, a Flair Neo works fine