I think that Merc is gorgeous. If the deal is right, I’d say go right ahead.
I’m in a similar position. Similar in that I’m coming to the end of my warranty period, I absolutely love the A4 and don’t know whether to change it or keep it. Similar also in that I don’t like what they’ve done to the A4 either. I don’t mind the screen in place of the wheel as I’ve always found the wheel too fiddly and hire cars I’ve driven with touch screens are much easier. What I dislike are the exterior changes - for me it’s starting to look like the A4 is trying too hard, a bit like a woman who feels she’s losing her looks and begins to over- compensate when in reality she’s still good looking.
Where my case differs from yours is that I bought my A4 outright and I prefer estates to saloons. The simplest solution would be to get an extended warranty and run it for another year, but then in a year’s time it’ll be worth less and I’ll have to find a larger amount to change. May be better to change now while it still has about 50% of its original value. As a replacement I’ve been looking at the Volvo V60. It gets very good reviews and they have recently introduced a 190PS 2 litre petrol turbo engined version. I’m very tempted and there are some good offers out there.
My warranty runs out on 31 August so I have a few more weeks to prevaricate.