Re: B7100 with 300 hours vs BX
heehaw,
I'm out of town right now so I don't have access to my Kubota informational brochures, so I recalling this information from memory (I'm getting older so the memory isn't as good as it used to be...).
3-Point Hitch:
The BX does have a 3 point hitch and live-PTO; the only problem with it is that the lift arms are shorter than what most implements are built for. Therefore, on some items, you have to buy equipment designed for smaller compact tractors. I have similiar problems with my B7100. I believe that most any type of implement is available for the BX (mid & rear finish mowers, rotary mowers, box blades, rotary mowers, backhoes [BX22 only], front-end loaders, etc).
Brakes:
As I remember it, the BX has only a single pedal for the brakes, thus it is not capable of diffential braking. I have two Kubotas and very rarely use differential braking, so I'm not sure how much of a problem that is. One time I hooked up a 6' (72") rear mower to my smaller B7100 (so I could move it from one location to another) and it kept the front wheels extrememly light, thus requiring differential braking for effective steering. Note that even here is wasn't required; I could've waited until I got my larger tractor (which normally uses the mower) back to the same location to move the mower.
Clutch:
The other significant difference between the BX and other tractors is that the BX doesn't have a clutch pedal. Apparently you (1) shift the mid-rear PTO in-and-out and (2) shift the hydrostat transmission from high range to Neutral to Low range without having to depress any clutch pedal. As I understan it, both the PTO and HST have to be in Disengage/Neutral in order for the tractor to start.
Hope this helps in the search,
Kelvin