Michelin Hydroedges are by far the best tire I have ever owned. After 7 years of faithful service, I replaced them with Michelin's new Defenders.
Relative to the Hydroedge, after four tanks of fuel, my initial impressions of Defenders are quite good. Noticeably quieter and more compliant ride. Same excellent wet/dry traction as Hydroedge. I do feel like the Defenders have more body roll on dry roads and maybe less lateral grip in wet/dry than Hydroedges (just don't feel they are as sure-footed or predictable as Hydroedge on some of our town's many, many roundabouts). Hydroedges required little steering input during highway driving, Defender's require more (less centered feel). Fuel mileage has improved by 4+% (at this rate these tires will pay for themselves over 90,000 miles). Haven't run them in the snow yet. If Defenders are anything like Hydroedge, I have no doubt that they will last 90,000 miles.
Overall, I feel Michelin has done a great job improving on the Hydroedge in important areas - ride, noise, traction, rolling resistance and treadwear. The negatives (compared to Hydroedge) are small and probably wouldn't be noticed by most drivers anyway. If your driving style is easy going or average, I highly recommend Michelin Defenders. If your driving style is spirited, you're probably looking at other tires anyway.