Originally Posted by name='Kempez'
Exactly, all of which reasons as to why I say SLI is a waste of time and money
Given that you're spending the same amount on the 2nd card and getting less for it you could say you have "wasted" some money there, especially when there is usually a single card which gives the same performance for less.
However, I think the argument changes when you're talking about performance above and beyond existing single card setups.
In that case there is no single card that can give the performance of SLI, so the SLI setup can be thought of as roughly the same as a single card which fits in at the top of the price curve.
If you graph the power/price curve of single cards adding the SLI options which give more performance than the top single card I suspect you'll find that SLI fits in about the right place in the curve.
Of course, when each next gen card comes out (I suspect) it usually gives more performance for less money than that SLI option. Once that happens the original argument of waste suddenly applies again.