Whatever you do, don't be swayed into buying a particular brand . Fit is more important than manufacturer or just choosing something because it looks good. Every saddle is different but key things that you need to look for when fitting a saddle are the following.
Put the saddle on the horse without putting a rug on it and tighten it with a girth. You should be able to get your fingers under the front of the pommel above the withers of your pony. Check that it doesn't fit too high or also push down on the pony's spine. If possible sit in the saddle and repeat the above procedure and you should get the same results. Also check the fit from the back of the saddle and also check that the saddle it doesn't impede any forward movement or your pony. The seat should be as level as possible but this can be rectified by a riser or good saddle pad. Buy something that is big enough for your pony and yourself but not too small or too big. Beware of saddle fitters who want to sell you one of their own expensive saddles.
Also if possible try and find as many similar saddles for your horses, that way you'll have the same setup when you swap ponies between chukkas which means that you can concentrate on your game rather than adjusting and altering yourself to your tack and you then don't have to think about your riding.
While I agree with everything you've said - I ive in Saudi Arabia, so I won't be fitting saddles on ponies, until the saddes get here.
I'm quite satisfied with the tack I have, but the other day I rode a friend's horse with a Stubben close-contact saddle, and thought - Wow! I feel like a diferent rider! Everything just worked better, and I now understand why this guy hates using mine...