400ixl

I have a 2013 E250 (A207) and a 2017 Hyundai Tucson. Whilst the Merc has some better quality materials, the Hyundai is far better bolted together without all of the squeaks and rattles that come with the E class. Technology wise the Merc is decades behind as well. The Hyundai has been more reliable, but then it is newer so that is to a degree to be expected and has the advantage of a 5 year warranty as standard in the UK, Merc one ran out at 3 years.

Not sure where people are getting the concept the E class will be safer, both have top rating and the SUV in itself is higher and safer for the occupants.

I personally wouldn't swap a newer Santa Fe for an older E class saloon in a million years. However, if you don't enjoy driving it and you want an E class then fair enough.

MaschioneCazzuto

agreed w212 are tanks unlike the new w213.

El Cid

I have a 2010 and M-B lost a ton of money under warranty. Good for me and dealership, but bad for M-B. Now I have a car with lots of new parts and updates, at least through 2016. While E350 is most reliable vehicle M-B sells, it is not as reliable as a Hyundai. Of course I am not sure about the Santa Fe Sport specifically.
One aspect is you are now driving a small SUV so no way is it going to compare to a sports sedan.
Big issues are that you are changing to a car that is 5 years older than one you have; a car that is not as reliable as one you have; a car that costs a lot to repair even if you DIY or use an independent; a car that probably has higher insurance, fuel, tax and other cost to own expenses. You will also give up a lot of practical features of an SUV.
M-B's are very complicated which is one reason why repairs cost so much.