I have done quite a bit of testing now. What used to be the situation with AHII was that SLI was not needed until you had reached the end of the CPUs potential and then wanted to use greater and greater textures sizes or environmental. So, SLI typically would not show any scaling, unless you increased the texture sizes, turned on shadowing, or increased environment settings.
With the alpha (it's still early) it is more important to tune the texture sizes for your specific resolution. Increasing resolution will almost certainly cause you to drop texture size, particularly at or above 1440p.
In both versions it is advantageous to activate the SLI scaling bar while tuning your system graphically, and regardless what your personal preferences are to configure for maximum scaling. If you do this the only setting of the Nvidia Control Panel that you need to change is (for now at least) the SLI rendering mode. Everything else can be set in AHAlpha and adjusted for maximum benefit (scaling).
Everyone's system will be different with SLI the way it is right now, and it is very likely to change I think.