I also have an HL-S7178W that has been ISF calibrated. PQ was very good out of the box, but is stunning after ISF calibration. The PQ, screen size, features, and cost are hard to beat.
I went with Samsung for this new set based on past experience (this is my third Samsung DLP), and comments from ISF calibrators at avs forum that it provides the most accurate picture after calibration.
I got an extended warranty for the first two sets, and used them once for a bulb replacement, but did not get the EW on the 71" set.