After having traveled over 6,000 miles on these tires, I figured it was time for me to put up my 2 cents worth about them so that others could benefit from my experience in case they were considering purchasing a set. A quick note before we begin: I bought these tires as a LRR option with a bit more of a "performance" slant. As always, I ran these tires just under max-listed sidewall pressure (42psi in this case).
First and foremost, let's talk about the impact on range: when I first purchased these tires on Black Friday of 2015, I was appalled by the impact the swap had on my efficiency. Just before the swap, I was getting 4.4miles/kWh on my OEM Bridgestone Ecopies @ 40k miles (I do a lot of freeway driving @ 65mph). Just after the swap, I was getting 3.6miles/kWh on the Pirellis on the exact same commute. Now, to be fair, at right about this same time we transitioned from a nice, mild fall to a full-blown wet and cold winter (i.e.- lots of defroster use and lots of water on the roadways). I was hoping that the situation would improve once I hit the more mild weather of spring and that has indeed been the case. Between the milder temps and the dry roads and the breaking-in of the tires, I'm now at 4.2miles/kWh. OVERALL A 4.5% DROP IN EFFICIENCY. Not too bad, provided the tire performs well in other ways...
Next up on my priority list was traction. As much as I was enjoying doing wanton spin-outs on the Bridgestones, I was really looking forward to getting a tire that actually gripped the road instead of skimming over it. The initial results were very promising, especially in crappy winter conditions. As the tire has broken-in, the traction has loosened back up a little bit, but it's still a pretty good grippy tire. If the worn-down Bridgestone's warranted a 4/10 on traction, the Pirellis are more like a 7/10; I can still get some decent wheel spin if I floor it while taking a corner, but the automatic traction control is not clicking on nearly as much as it used to. Grip in the wet is particularly impressive. I wish I could comment on snow & ice traction, but we didn't get any weather like that this winter in Seattle.
Closely related to traction is the matter of braking. I normally don't have much occasion to put my panic braking to the test, but the other day I had a car cross right in front of me on the freeway on its way to colliding with an SUV alongside me and, let me tell you, the braking of these tires was phenomenal. Luckily I didn't have anyone behind me because these tires helped me stop QUICK!
Finally we get to the odds & ends bits: noise & ride comfort & handling. In terms of noise, I'd say these tires are right about even with the Bridgestones. They're not a "silent" tire by any means, but they're not too bad at all. Ride comfort, on the other hand, seems a bit improved. This isn't something I notice in most of my driving, but every now and then I hit a pothole or a railroad crossing and I am amazed at how well the Pirellis seem to soak them up. General handling is likewise very good on the tires, but there is one big exception: rain grooves and bridge decking. Compared to the Bridgestones, the Pirellis like to track quite a bit on rain grooves and bridge decking owing to their prominent rain "gouge" running the circumference of the tire. I'm sure this groove is part of the reason why these tires do so well in the rain, but they have the downside of causing the tires to become quite squirrely when you're driving along a road with prominent rain groves running the direction of traffic and/or bridge decking with a similar orientation.
So there you have it. I'm overall happy with my tire purchase, though it's taken me a while to get back to a point where I feel my efficiency is acceptable. As it is, I'm willing to give up the ~5% in efficiency for a tire that performs better in most all ways than the Ecopias.