[XLcommerce]

Supporting IE means taking on board a technical debt that will follow you for the life of the project. There are lots of things that can be accomplished in ie6 but then you need to consider performance. If you're building an app that means a lot of JS and possibly DOM manipulation... which is dog slow in ie.6,7,8

Now factor in support costs. I can picture it now:

Customer: Uhhh your app sucks it's so slow.

Support: Hmm looks like you're using IE6. We've worked really hard to make our app function in every browser, however if you'd like the best possible experience then please upgrade.

Customer: What's a browser?

The best solution is to use chrome frame. The installation can be made seamless and if your app is worth using then your customers wont mind the extra 60s it takes to install.

[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.