I agree with ILUVMILS. See if you can drive one for a while.
Technology marches on. Is more technology better? Can't answer that for anyone but myself, but...I would love the S500's 5 speed electronic tranny and air suspension in my E500!
BTW, other than having the A/C in the S upgraded to the later system under warranty (early builds had weak A/C), the S has been very reliable up to its current 43K miles.