Sir,
It has been my limited experience, that if I settle on something that might be "a little too little" for now, I hate it later. for example - I bought a 471 over a year ago - and my needs were for a 50 pto hp, fel, etc.....I added roughly 20% to what I thought I needed, and bought the 471 (60+ pto hp). and I'm really glad I did - otherwise, it wouldn't pull the 4X5 round baler..
simply put, buy more than you need. In my case, I always figure what i need (whatever it be), then add 10-20% to the capability. Usually, that gets me there.. Another example...If you need a medium-duty 5 ft bushog, I'd recommend buying a 6 ft....or a 5ft heavy-duty...
ain't nothing better than "new tractor arrival day" though, whatever you decide.
SM