There's just no comparison between the ECB and the WSM. The fact that they're similar in shape and style of cooking is misleading. In every way, at every level, the WSM will outperform the ECB, and very easily.
Many start with an ECB simply because they're not aware of its shortcomings, and the price is temptingly low. Once one attempts to actually use the ECB, its inferior design and quality become glaringly obvious, and regret sets in.
The price difference may seem considerable, but in reality there's just no fair comparison. The WSM is so vastly superior to the ECB, it's like trying to compare a home built go-cart to a fine automobile.
In addition, one must consider customer service. Weber's customer service is legendary, with many board members posting gushing reports of courteous agents, and speedy shipping, should there ever be a need. Weber products are known world wide as quality products.
And finally - since you're a registered member - you obviously know that this is *the* place for unbeatable support. Chris has provided a platform upon which an entire community of BBQ champs, personal chefs, backyard experts and average joes share and teach each other tips, tricks, recipes, and disasters -- and all of it is WSM specific. In my opinion, and I've looked around, there's no better forum for such an exchange.
You know, when you think about it, the difference in price kinda seems worth it.