Several years ago I thought I would make a fortune on a mechanical system which only looked at 1000m races at MV. It looked promising and then the powers that be decided the track should be closed to be relaid and I gave away that system for the duration and frankly, forgot about it until I saw this thread. The basis of the system, for anyone who might want to check it out now (and possibly at other tracks) is that the chances in 1000m races can usually be very easily identified.
Rule 1. Only for 4y.o. + 0r 3y.o. after February.
Rule 2. Initially look at horses having at least 3rd start from a spell.
Rule 3. Consider only those who have have min 50% of all their wins at 1000m.
(e.g. 5 career wins, would need => 3 wins at 1000m.) If more than one go by barrier or even skip the race.
Rule 4. If no selection from the above, best 1st up record amongst the first uppers this time in.

The point is that 1000m races are usually won by 1000m specialist horses. That's my feeling anyway. Most horses, as has already been mentioned, are using this distance as a conditioner but if they are still racing at 1000m after 2 runs in they probably are being aimed at a win at 1000m.

I'd be interested to hear if any statsman could give some data on the number of 1000m races won by horses that don't win at any other distance. Might be too hard to specify those criteria in a database search.

Cheers