Edge 830 vs 840 130€ difference

I'm planning to buy a edge cycle computer.

Initially I would go for the 540, but because I want to use the navigation feature I fear that the lack of touch screen will make it a frustrating experience.

Hence why I've settled on the 8x0 series.

I can get a used 830 for at least 240€. Whilst a 840 will set me back 370€

What is making me consider the 840 is the improved UI and the customization through the Garmin app.

Apart from that I will only use it for occasional navigation and showing stats during a ride.

Is the difference in price worth it just for this?