Looking at buying one, they tend to be a good £1000 more expensive with the kia unit installed, plus map updates will be expensive and not as up to date. Aftermarket units tend to be £400 for a really good one that runs apple car play and android using Google maps which is free and you can use 2 cameras. So for less that the extra £1000 id save i could upgrade to a better unit thats future proofed and more advanced.
For £10k I can get a 2016/ maybe 2017 with sub 50k miles but no nav. £11k to £12k would get you a 2018 base model at a push, but nothing necessarily newer. Id rather pay 10 grand for a decent 2016 and upgrade the nav myself I think. The grand id save wouldnt get me anything newer, just the trim level which I can do better myself for £500 if you see what I mean.