My brief comparison of features and pricing wasn't about whether or not you are going to offer insulation, but whether it was included in the price of the fermenter.
Furthermore, I'm not sure that a spray ball mounted all the way over to one side of the vessel would be an effective way to CIP. CIP is most effective when introduced at the vessel's highest point, with uniform pressure, spray pattern, and no shadows.
In addition, I'm not sure what a 4 PSI pressure difference in a fermenter really offers a home brewer, It's much more than you need to transfer, but far too less to carbonate.
For those guys looking to ferment under pressure using a spunding valve, you would be better off with a tank designed to hold greater pressures. When on the rare occasion a professional brewer ferments under pressure in our Pro Tanks to suppress ester production they typically do it up around 10-15 PSI. Since our Pro line FV's are rated for 30 PSI total, its safe.
However, that is typically done to either increase fermenter turn times or impart a unique flavor characteristic. Yet, if done with the wrong yeast strain, adding pressure can stall fermentation, which could negatively impact the outcome.
Lastly, capping a tank without a capable PRVR is something that could damage a vessel or injure someone.