Roger,
Steve Carver's web site is a good place to go for information when wanting to compare models (there are usually links from this forum's opening page).
Here are my comments...
Power Steering: If you are going to use a Front End Loader (FEL) then the predominate opinion on this board is to opt for a tractor with power steering to make life easier. The
B7400 has manual steering while the
B7500 has power steering.
Transmission: Again, for FEL work, go with the Hydrostatic Transmission. Especially if there is a lot of fore-and-aft tractor movement during the FEL work (I'd guess that greater than 80% of all FEL work involves a lot of changing direction...at least mine does). The
B7400 is available only in hydrostatic; the
B7500 is available in both gear-drive (B7500D) and hydrostatic (B7500HSD).
Both of the 3-point hitches are category "1" hitches. Neither tractor has position control on the 3-point lift. You'll have to consider the next larger tractor (
B2410) to get position control if you think that you'll need it.
Horsepower ratings (based upon the sales brochure) is as follows:
Model Engine HP (PTO HP)
B7400HSD 16 (12.5)
B7500D 21 (16)
B7500HSD 21 (17)
That should be enough information to pass along for now. If there are more questions don't hesitate to ask. There is plenty of wisdom and experience lurking within the members and readers of this board.
Kelvin