Bedder :
You cannot stress the catch all "runway behind", "fuel in the bowser" and 'air above you" enough in our business. As a proffesional pilot you try and have everything going for you. I would ask. If it was not possible I would then choose. It is always better to ask.
As a re-enforcement read the recent threads on the two rnwy incidents in the last few days. Firstly an Air Canada A320 rejected in LAS and took a long time to stop. Secondly a Biman a310 aborted rather spectacularily after starting to rotate (speculation). The end result is found here:
http://archive.gulfnews.com/articles.../10110582.html
Check out where they stopped. The keys would indicate they are within 1500' of the end. The A310 is alot lighter than a loaded 777 or 747 and so similar inciident with a larger airplane would have put the aircraft off the runway. Maybe by 200 - 300 feet who knows ! This of course without arguing the merits of this particular reject. At the very least if you do have to reject due to catastrophic problem (bird strike + multiple flame out etc.) at or close to V1 with older brakes, tires, rubber deposits etc., that extra length means you will be going slower if you off or you will stay within the runway length.