Perhaps you are thinking of the 1D3 AF problem - the 1DS3 has always had good AF.I always knew about this problem with the 1D3, but read in a forum elsewhere that the 1Ds3 also had this problem - it's possible that that person didn't have their facts straight.
The 1DS3 is a straightforward stills camera with no video etc - but the IQ is stunning. It has a shutterlife expectancy of 1/4 million so should last a long time.Arrghh now I really don't know what to do!
For a landscape camera it has all the features you want including firstclass weather sealing, it is also pretty good at sports and fast moving subjects.
Useable ISO1600 images are fine for me, and I have NeatImage Pro for anything a bit too noisy.