[brudgers]

Leaving aside the appropriateness of lumping IE6 with IE8 and 9, the support costs are already in the $100,000 number.

Slow speed of execution in IE might well be considered a vast improvement compared to the current state of affairs in regard to the potential customer's standpoint - i.e. IE not working at all.

Again, "change your browser" is a poor way to convince the customer that 4ormat.com is worth using given that the customer has already responded to the call to action.

Indeed, one might argue that there's no excuse for failing to inform the potential customer that IE is not supported before the call to action is clicked - obviously 4ormat.com is capable of testing for browser versions.

[XLcommerce]

Seems win-win to simply use chromeframe. Given this is a web app which presumably customers are already invested in using (since they're paying for it), requiring a 60s one-time install seems like the best course of action for everyone involved.

Slow speed of execution in IE might well be considered a vast improvement compared to the current state of affairs

Unfortunately the general public doesn't think like that. To the average Joe your site is slow therefore it sucks.