I don't think that the star mentality applies to Simao, yes he is Benfica's Gerrard, but if you see him play for Portugal, you would realise that he is a team player.
You made a good point about him not being as active as Liverpool may need, but he can do some great things with the ball, he runs a lot, atacks and defends. Plus, this season he is on the playmaker role, so he is more resourceful than you might think he is.
I can see him adapting to the Premiership and being an important player at Liverpool.
........Xabi.....Mascherano
Gerrard....................Simao
..........Crouch..Kuyt/Voronin
That looks great.
However, Benfica's president seems to be keen on keeping Simao.