on the other hand, IE6 masquerades as a modern, supported product, when in actuality it’s an eight year old vestige. in some cases, it requires an almost equivalent share of development effort to produce (what our clients and users expect) in it.

my official stance, i suppose, is no negative user experiences for anyone. but there are degrees of effort to make an equivalent positive experience for every user – and you must judge whether to spend that time based on your audience.