Weight is largely overrated.

The opinion that the longer the distance the less the topweight or higher weighted horses win has no factual evidence to support it:

Take for example the strike rate of horses carrying 57kg's or more by distance category. Fgures are for every race M/P/C 1/1/04 to 18/7/04 (excluding hurdles and steeples:

800-1199m 14% SR (2976 races)
1200-1599m 12% SR (6410 races)
1600-1999m 13% SR (2130 races)
2000-2399m 13% SR (695 races)
>=2400m 15.5% SR (only 135 races)

Alternatively, examine the strike rate of TAB number 1 over the same distance categories.

800-1199m 18% SR
1200-1599m 15% SR
1600-1999m 16% SR
2000-2399m 21% SR
>=2400m 20% SR

One of the greatest challengers losing punters face is letting go of so called universal truths about racing. i.e. the effect of weight up / down, lower class races are bad betting propositions, don't bet on wet track etc. etc. Most of them are simply untrue.