My Yeti has the Amundsen which was also available in the Fabia and Octavia (at least). The Columbus and Amundsen+ are also available across all three models (possibly the Superb too but not sure) and there are plenty of units available online in places such as E-Bay.
As for fitting, there will be a couple of things to look out for as far as I can tell:
1. Is all of the required wiring in place? In particular wiring for the GPS Antenna and, if you're considering the Amundsen+, a suitable DAB antenna (I'd love to know whether you can hook up a DAB receiver to the standard FM antenna as I'd consider upgrading my Amundsen to a + unit if it was a straight swap).
2. I think you'll need the new device coded to your Yeti.
3. Do you have a maxidot in your drivers display? The factory nav units display 'next turn' instructions on the maxidot. probably not the end of the world if unavailable I suppose.
Otherwise you might like to consider a Garmin / TomTom unit and a Parrot BT as including fitting, they'll come in much cheaper than the cost of the Amundsen/Columbus units.