We're considering buying this seat for our son (17 lbs but too tall for his infant seat) and thought the extra 25 pounds limit (max 65 instead of 40) would make up for the higher cost. But will we really be able to keep our seat that long, or do they get trashed by use? (We're pretty good about cleaning up after our son, but he's very active.) Also, do changes in safety standards and technology make it unlikely we'd WANT to keep it that long?

IIS