>No, M-B never manufactured (for series production) a 260E 4-Matic (neither in Germany nor in the U.S. as a 300E 2.6 4-Matic.
Sorry, but this is not true.
Mercedes did produce a 260 4matic sedan, maybe it was not exported to the USA. Internal number of the 260 4matic is 124.226.
4matic was available for the sedans 260E (124.226), 300E (124.230), 300D (124.330) and for the estate 300TE (124.290), 300TD (124.393).
Concerning 4matic in general: it is great, if you really need it in deep snow or sand and in the montains or woods.
On the other hand 4matic is very special (lots of parts wouldn't fit from the 2wd sedan, even floor mats are special), it is heavy, has a bunch of additional parts that may break and repair is expensive - if you find a trained technician at all.
As Neil stated, there are no aftermarket springs for the front - exept from AMG or Brabus -> $$$$
The smaller 6I-engine will need a heavy foot to accelerate the car, so gas milage will be poor.
Again, if you don't need the 4matic - pass the car.
improve your German - please visit my homepage :-)