I've recently replaced the Columbus in my '09 Superb with an android unit from a company called Joying.  I don't have the time to write a full review at the moment, but happy to try and answer any questions if anyone else is thinking about doing the same.  Especially as I found information very sketchy when I was researching before I took the plunge.

 

Overall I am very happy with it, but it is not something to do if you're expecting a straight forward plug and play - you need to do a some tinkering and there are some compromises to make.

This is what I expect to do if my Columbus ever dies. Can the new unit read the car's road speed and steering angle from the CANbus? It's one of the things that makes the Columbus very useful if your route involves tunnels or steep sided valleys as it doesn't need GPS data at all times to update the car's position.

 

I've turned off all the messages that pop up when you adjust the aircon, so I won't miss them. 

 

Do the remote steering controls work for you? I would miss that.

 

Also does it have to be connected to the internet to get mapping data for navigation? I love the traffic feature in google maps showing congestion and estimating ETA based on this, so in Ireland that would be better than the Columbus as traffic updates are subscription only in Ireland and are more than likely only available in Dublin anyway. The worry with using google maps is getting shafted for data fees when I'm driving outside my home network.

Apologies for not replying sooner, for some reason I did't get an email notification when you posted.

 

I'm not sure about reading the speed/direction from the CANbus - I will need to test it when I can, next time I go through a long tunnel I suspect!  The unit comes with a separate GPS antenna, but I found an adapter for the built in one and that works great (I didn't fancy wiring in a new antenna).

 

The remote audio steering controls all work, volume up/down, mute, track skipping etc. Phone controls work as well, although not quite as slick as the old built in bluetooth integration - but I think that is to be expected.

 

For nav/maps I have a number of apps, Google maps is great, but as you say you need data - I tether my phone (the unit has wifi) and have unlimited data, so it works great, so long as you have signal/coverage.  I also have NavMii and CoPilot, both allow map downloads for offline use.  NavMii is free, with some cheap in-app purchases for upgrades like additional voices, traffic, etc.  CoPilot is about £20 I think (bought it a couple of years ago to use on my phone), but works great.

Hope that all helps.  If I get a chance to test the nav in a tunnel I will let you know if it works.