Surprise! Turns out that you don't have to brick your console to escape the long installation times of the Wii U system software update. As it happens, you can have it download in the background while you're enjoying NintendoLand and New Super Mario Bros. U.
How do you do this, you ask? Apparently, it's as simple as setting up your Wi-Fi connection and then pressing 'Cancel' when prompted to download the update. This way, instead of plaguing your Wii U GamePad with a progress bar, you get to play your games while the 1GB update quietly downloads in the background.
When you decide to update, the thing will have been fully loaded into your system and will immediately install, taking only around ten or fifteen minutes to complete.
While it is a solution that renders itself apparent to anyone with a shred of sensibility, it's not necessarily clear that pressing 'Cancel' will automatically make the update download in the background. Perhaps Nintendo needs to release another update to address that (good God, no - Ed).
Thanks to the Reddit user who discovered this
(and the GoNintendo chaps who verified the claim