Heres a thought...
When does the import file of ME 2 kick in ? At the end of ther story but what about other side stuff you do after but more important the last DLC "Lair of the Shadow Broker" changes a lot of things so how will that be in ME3 because not everyone would of played it.
Also I got Kasumi in my male playthrough after the main quest (DLC was not out at the time) but got her before in my female one. So how will she be in ME 3 ?
I loved the DLC but it seems that it could complicate ME 3 a little with the transfer save.