I''m not sure it is a Giant... I have never seen one of their compact frames with gear lever bosses on the frame - it might have been added on but if it has then either the cable bosses will still be there, or there will be marks remaining where they have been removed. The earlier horizontal TT frames do have them though.
And I can't see it well in the pics, but is the seatpin clamp an integral part of the frame, or an external band on type? I have only ever seen compact alloy Giant frames with the external band type
not saying it's not, just it doesn't quite seem right but that might just be becaue it's hard to see in the pics