It's hard to believe McLaren could try to get any significant aero data at, of all places, Monaco. My belief is that each driver is havcing their car developed to suit their personal preference. That way, neither can claim the car was optimized for the other and didn't suit their personal style. For Montoya, that removes excuses. Fot Kimi, it shows to him that the team is willing to go to any measures to give him a winning car. Even though he may already be contracted to someone else.
Qualifying will be exciting. No one can wait to the end and hope for a clear track, it's just too close and unpredictable. So everyone wil be going flat out right from the start, not taking chances that at the end of a session they may find themselves behind Sato, Or JV, or anyone else.
But the start of the race will be something to look forward to. I seriously doubt if both SA's will get through the first turn without mishap.
Monaco is just too unpredictable, I expect Renault and Alonso to play it safe right from the start, and be willing just to finish in the points. The best way to do that is to qualify first, even if it requires much less fuel than normal. Getting safely through the first corner is probably their main concern right now. I would not be surprised to see Alonso qualify on the front row, but make his first pit stop early, to hand the lead over to someone else.