No TXAA with SLI and Borderles window mode creates fluctuating peformance

Hi,
After finding the workaround to start the game I find that TXAA is not available whilst using SLI, isn't this meant to be both supported properly out of the box?
I have been holding off playing the game proper since I got it due to the initial not being able to start the game and having to mess with the ini fles.
It should no be the case that people have to do this to get the game to work, it is silly.

I find borderless window mode to be rather problematic with performance, EG Tomb raider , Hitman Absolution etc (I know these arent Ubi games but they good examples of borderless window mode causing issues)

so I ask why does fullscreen not work? there has to be a reason
and why is TXAA missing when SLI is enabled?

I tried logging a support case with Ubi but conveniently the system was offline!!!

Here are my specs:
I7 3930
GTX 690
16gb DDR3
500gb SSD

Thanks