Keep in mind that tracking in the Midwest or East you will be tracking on lead - most folks use a 10 meter or 30 foot lead. In the South and Texas most people track off lead, and the breeds used different places work better for one situation or another. Remember too that you will be following the dog...which is following the deer...which will go thru the nastiest places they can find. One of the advantages to a smaller dog is that you don't have to waterski thru the multiflora rose thickets...my hat is off to guys that track in the thickets with a big dog. I can't imagine being pulled thru the stuff we go into behind a 120 lb bloodhound!
Check into the prey drive of the various breeds and breeder's dogs too...this is a balancing act... you WANT strong prey drive for tracking, but if you have a really strongly prey focused dog - a good hunting Teckel or a well bred Jagd, for instance - forget about keeping a cat around. For us this doesn't matter, but if we brought a cat into the house with Oskar I suspect it would be in small pieces within about 15 minutes! The dog needs to fit YOUR situation - these working breeds, from what I've been exposed to at least, are NOTHING like the beagles and hounds I grew up around.
R