wbender,
I guess that I am spoiled. I have two Kubotas; one with a mid-mower and one with a rear-mower. I use them both on a regular basis (or should I say that my wife and I use the two tractors...). Here are my opinions:
Maintenance: With regards to maintenance, the rear mower is much easier when tasks such as blade sharpening is required. Mid-mowers typically require you to remove the deck to access the blades.
R&R: With regards to installation and removal of the mower, the rear-mower used to be extrememly easier, but with modern mid-mower designs, the difference has been reduced, but the rear mower is still easier to deal with.
Storage: When storing the tractor with mower attached, the mid-mower has a decisive edge as it takes MUCH less garage space to store.
Availability: Rear mowers are readily available, and can be assumed to stay that way. Mid-mowers are typically custom designed to the tractor; therefore, chances are that at some time in the future the mid-mower that is available today may no longer be available.
Cost: The custom built mid-mower is almost double the cost of a rear-mower.
Issues with Mowing...
Maneuverability: The mid-mower is much more maneuverable than the rear mower. Plan to let someone with lower operator abilities mow?
Breathing Dust & Debris: Have allergies? The rear mower offers the advantage of having the discharge chute located much further away from the operator relative to the mid-mower. A rear discharge mower is even better in this regard.
Hard-to-Reach areas: The rear mower allows the operator to put the mower in areas that would be impossible for mid-mowers. For example, I'll use my rear-mower to mow over the edge of a bank, over the edge of a river, or under tree limbs.
Stability: I feel much more comfortable mowing questionable slopes using the mid-mower than with the rear-mower. If I mow down a slope with my 3-point mower and am not perpendicular to the slope, the mower will have a tendancy to push the tractor sideways as it obviously wants to travel down the hill faster than the tractor is moving.
Bottom Line: I think that answers to the "which is better" arguement varies greatly based upon the answers to the following questions:
(1) What is the percentage of time is the tractor used for mowing?
(2) Does the area to be mowed dictate one type over the other?
(3) Do you frequently use the tractor for other tasks that requires the mower to be removed?
The majority of my tractor's operating hours (80%?) are used for mowing. In general, I actually like mowing with the mid-mower best, when the area to be mowed allows. This statement assumes that I am comparing a side-discharge mid-mower with a side-discharge rear-mower. Since I like rear-discharge mowers better than side-discharge mowers, I usually end up mowing with my 72" rear discharge 3-point mower.
Good Luck,
Kelvin