I think £250 is alot for a Dashcam myself especially if you need an add on for it aswell. Keep checking their website, they have DFS style 20-25% off offers on every weekend on all their Dashcams plus if you use the Nextbase 10% off code on top you can pick up some bargains, I did on my 522 afew months ago got it for less than £140 with the rear window camera. Though they probably won't do it on the 622 for a while being new out. But when I see the 622 at a decent price I'll dive in and purchase one and probably sell my 522 or 612 on to fund part of the upgrade.
Looking forward to seeing some footage once people start getting their hands on it, especially night time footage as their last 4K 612 camera wasn't the best in the dark. Even knocking the resolution down it still wasn't great.