Customization has been curtailed to a large degree on all newer models. No more custom 'chevron', no custom splash screen, etc. You can still add a few things, though.
When you say 'route planning', do you mean just point to point, or multiple stops? How many stops in your itineraries, and are you preparing those off-line or on the device?
That kind of planning is available on all current units, so you won't be missing anything there.
Last question - should have thought of this sooner - was your 940 a "Live" version? Did it make its own connection back to TomTom for traffic? How have you been making that connection?
Oooo... would have been nice, and even nicer now. Let's go with the less expensive option, though, that allows you to use your phone to transmit the traffic data to your device. There's a version in Europe that has it's own built-in cellular capability, but that raises the price quite a bit.
Available from many other sources at various prices. You will see both a 5" and 6" screen version, either of which will be a boost over your 940 in that regard. Warning: Once you get accustomed to 6", it's hard to go back!
That is definitely a Nav4, Arno. No Nav3's left on that page! It also has the nice "Prato" mount.
The 6" is 162mm (~6-3/8") W x 105mm (~4-1/8") H. I don't have a 5" unit of that style handy to measure.
You can score the 5" version on Amazon in the UK for £145.98. 6" goes for £168.00 on Amazon... quite a bit less than the listed MSRP prices on TomTom's site.
Either will be a surprising improvement over the 940 screen, but if you can swing the 6", I think you'll really love it. Another feature of these units is that you can increase the size of buttons/fonts/etc so that if your eyesight isn't exactly 20/20 these days, you can use that 6" to increase the size of things a bit without losing a lot of content.
I think you're really going to enjoy the screen, but it will take a little while to get used to the new user interface. It is now 2 generations away from the one used on the 940. If you have any questions about using it vs. the 940, feel free to drop back by and ask.