As a young pup, I studied and adopted the expert methods of Clif Carey in relation to my introduction to race/weight-handicapping. One of the methods outlined by this master form student with some help from his "off-sider," "Phar-Lap", was the relative differential between particular horses. Using the acknowledged ratio of 3lbs(1.5kg)=1 length , these principles stood the test of time until the more recent era. No, longer can you say that a rise in weight will necessarily adversely affect a horse's anticipated performance by a uniform degree. What I mean is that in a previous race , Horse A carrying 55kg may have beaten Horse B by one length(1.5kg). Next race, they meet again with Horse A raising in weight by .5kg and Horse B lowering in weight by 1.5kg. You would expect that Horse B should win their next meeting but how often does Horse A win again or beat it's rival in finishing order? Has racing changed that much?.
Then in the 80's along came the inimtable Don Scott with his revolutionary "new fangled ratings method."
Again, my methods were refined and today I mainly restrict my investments to opportunities which offer a percentage advantage, whether they are by way of dutch-book, exotics or strategic place betting.
It seems that racing may have turned full circle and the way of the future may once again be the evaluation of a particular horse's anticipated performance in relation to other particular horses.
I'd like to get opinions from a cross-section of forum contributors whether racing has changed so dramatically in such a short space of time.

Cheers.