^^^
Yep - do just because you want to and the bug has bitten.
As for compatibility - don't have us do your research. Go find back to the store and look yourself. I think the S2 uses a proprietary aero seatpost, so that should be included. I also think it uses a braze-on FD, and the Giant likely has a clamp-on so that would be a new FD. Does the Cervelo come with the headset? If not yet another extra purchase. Finally, depending on where the cable stops are your current cable set may be too short and you would need a new cable set. If too long then you can just cut it down.
Otherwise no issues.
Ugh, I just spent 4 minutes stating the obvious.