I just think if we are building a team to be peaking in 4 years time that he has potential to be a world class player whereas Cole, Aquilani etc do not. Not that I am not delighted to have them in the squad for the time being. It does appear (as it was last summer) that our midfield is going to be packed out with what looks like Diame, Sigurdsson coming in along with Cole, Aquilani and Pacheco's loan returns. Somebody will be on their way out!
On another note, Sigurdsson had been on Readings books since 15 so he might well count as homegrown.