Most SV's have had these removed that I have seen. Our Clubs old 252 we just unbolted it and hung it out of the way, as we did not use it..
I'll register one user who is damn glad that his SV252 still has a working driveline brake.
On mine, it had both the manual and hydraulic brake-steer actuators, but the manual components were junk. So I removed them and made up spacers that allowed me to run
only the hydraulic actuators. I rarely used that driveline brake except to shift gears. Everything was working okay...
...until I was pulling a compactor up a steep uphill section and ran out of gas. Guess what? The hydraulic brake-steering doesn't work so well without the engine running.
Now whatdya do? The driveline brake worked just fine, but unless I kept my foot into it the cat wanted to roll backwards downhill into the compactor.
Lucky for me, there was still an old 2x4 laying on the passenger floor, which I was just barely able to reach. Even more luckily, it could be jammed between the brake pedal and the seat back to work as a parking brake.
Anyway, I'm a big fan of a properly working driveline brake system (and a full gas tank)!