BikeRadar announced that Trek is releasing an aluminum version of their Emonda frame. The frame is listed as 1050 grams unpainted. This is curiously less than the Emonda S series carbon fiber frame, and comparable even to the Emonda SL frame. Here's a blog post where an Emonda SL was weighed at 1040 grams. So only the Emonda SLR is substantially lighter. Adding paint the the Emonda ALA aluminum model would likely increase it to closer to the Emonda S, but brushed Al frames look pretty good.
Trek Emonda Al
Criterium racers get excited over Al frames because they can be made very stiff and yet there's less concern about crashing them than expensive carbon fiber. And with a bike like the Trek coming in within a pound of the lightest commercially available carbon fiber frames, the weight difference on anything other than extended climbs is almost trivial. Indeed the Cannondale CAAD-10 has such a dedicated following that Cannondale sells it with near-top-end components, including this nice SRAM Force version, and has sold it with Shimano Dura-Ace recently.
So is the Trek the CAAD10-beater? The weight numbers are certainly comparable.
The key is geometry. The Trek Al Emonda comes only in H2 geometry. The SLR Emonda comes in either H1 or H2. There's a substantial difference in reach versus stack, equivalent to around a 2 cm difference in stem length. Here I compare the Trek geometries to the Cannondale Evo and CAAD10, which are extremely similar.
The Cannondales zig and zag on the plot between the aggressive H1 and much more relaxed H2 but are generally closer to the H1 (note if you're looking for a particularly low stack this chart suggests you should pick your frame carefully). Meanwhile the Treks are designed to a stack-reach curve, following the first example of Cérvelo. But crit bikes are generally designed to be aggressive and overall here I think for most racers the CAAD10 is going to be the better choice.
Now if they came out with an H1 version...