if you wanna be cheap, like you are sounding, then that's what you are gonna get, I run scag and wouldn't go with anything else except an exmark. I have a 61" scag cheetah with a 34hp cheetah and i wish i would have went with a 61" turf tiger with cat turbo diesel, the fuel savings would have been enough to pay for the diesel option in a few short years, by using off road diesel. and yes 27 hp is underpowered for a 72" mower, i would go with the exmark, you say are getting an " equine discount" and think exmark mowers are expensive, but yet you probably have a 20,000 dollar horse trailer, and probably over 100,000 dollars in horses if not a million even. if you want a cheap mower, buy a bad boy mower or some of the other POS mowers you listed. if you want a nice mower that will last, and give you a nice quality cut buy an exmark or scag. end of story....or call a local landscape company sounds like you are ready to own a commercial zero turn mower. sounds like you need to just keep using your antique equipment and save your money.
fully lic. and ins. 10yrs exp.