If you ask why it is better to downgrade iOS 8.1.1 to iOS 8.1. Here is answer. The Apple company just launched iOS 8.1.1, which kills the Pangu8 jailbreak. The only good news is that it is still signing iOS 8.1. This means that you have time to install iOS 8.1 and jailbreak your device.
But you should act very fast. Apple can be very unpredictable when it is going to closing its signing windows. You will not be able to upgrade or downgrade to iOS 8.1, after the window for iOS 8.1 will be closed. You’ll have to upgrade directly to iOS 8.1.1, which will make your device unjailbreakable.
If your device not jailbroken, or if you’re still running iOS 7.1.2, it’s time to update to iOS 8.1.
But if you has already updated to iOS 8.1.1and in future you plan to jailbreak your device you should better to downgrade iOS 8.1.1 to iOS 8.1.
Follow these few steps to downgrade iOS 8.1.1 to iOS 8.1
Please note: At current time you can downgrade iOS 8.1.1 to iOS 8.1 though iTunes, because signing window for this firmware is still open for users. But hurry up because it can be closed at any time.
Step 1. Please download iOS 8.1 firmware for your device.
Step 2. Download and install on device the iTunes latest version .
Step 3. First enter DFU mode and connect your device to the computer.
Step 4. After iTunes will detect your device being in the Recovery mode click Restore and hold Shift/Option button on Windows or Mac.
Step 5. Select the firmware you need and that’s it. The work is done.
Note: If iTunes doesn’t allow you to complete this process that means that Apples closed signing window.