My point is that building a prototype that won't render correctly in IE (i.e., the browser likely in use by the commissioning client) as it's described in that

My point is that building a prototype that won't render correctly in IE (i.e., the browser likely in use by the commissioning client) as it's described in that article is counter-productive. If the client can't see it as it's intended, what's the point? Building up the prototype to a point where it is universally compatible will have two end results: 1. The designer is building multiple functional pages and putting in all the labor required. 2. The designer is providing the client with a nearly fully-functional page/site prior to full payment being received.