Hey Duritz, that's one of the most inciteful posts I've seen for a while, how lucky we are you didn't go off in a huff after your beer thread was so insensitively cast into the abys. (Your proper additions to the thread are quite interesting too :-).
I'm going to consider reassessing my way of calculating overs as a result of your thoughts on the extra problems which may be encountered by shorties.
I suppose it's possible to assess to some extent the truth of what you say. Over time if your theories are correct the very short priced horses should actually lose more often than their abilities would suggest. If the betting market is as accurate as many people here like to think we should get some sort of regular graph of a horses price against rate of winning (or amount returned through winning bets if you like). The graph should show a downturn around the odds on mark if indeed these short priced horses are getting stomped on by their fellows - run dead or whatever.
Of course there is the possiblility that the average punter is making allowances in the same way you are and the graph will be a straight line but if they are all that clever I might as well give up anyway.
Nevertheless, my own ratings which have no such dead/stomping factor should show some sort of variation.
Anyway, thanks for that post, it's given me something to think about.

KV