I can tell you that this is going to drive web designers absolutely bugnuts mad. Leaving aside the tracking issues (you’d best believe every web marketing/SEO agency on the internet is going to try and find a workaround) people are already used to the idea that you can turn an Illustrator design into a pixel-perfect web page. The bosses are going to ask about those ugly gray bars around the edge of the page, and it’s going to be hard to explain that Firefox is doing that against their will.
I used to work for a web design firm and they were insistent on all the bells, whistles and beautiful alpha-shaded rounded blurred shadows working on every browser from IE6 up (I imagine they’ve since revised their supported browser list). Not being able to control the “experience” at every stage will make some companies either abandon Firefox support or death march their developers into a “solution” of some sort.
