We have the Primo Viaggo, and it's held up great, about to get started on kid #3 (due in April). It is a bit heavier than some of the others, but nothing we couldn't deal with (I'm 5'7" and 140lbs when not pregnant). DD did outgrow it at 9 mos., but she's a big kid (90%). It also fit just fine in a Ford Focus and a Toyota Matrix--Britax seats won't work in many small cars, including ours, b/c they're too big. In short, it was the best, safest seat we could fit in our small cars, and we were happy with it. We did not, however, go with the matching stroller, mostly because of price, but also because size was a major consideration (again, b/c of small cars). We got an umbrella stroller from Target for $60 that would hold the carseat, too, and it's been great for us. It may not last through this kid, but even if we have to replace it, we'll just buy another one, and at $120 we'll still be cheaper than most of the other systems.
GL!