How do they compare ? 1 does the 72 scalp alot more than the 66 or 60. ? 2 I like the way you can get a 60 to run on a 25 HP motor,just how much more power do you need for the 66 then 72 compared to a 60?. I know water cooling makes a engine last way longer but is it worth the hassesl of the maintenance it requires? 3 How good is the 66 so far if I get a 72 I have to buy a new trailor. THANKS!!!