I'm running a D44 with 33's on my van that weighs in at about 8500lbs with about 170K miles on it. The brakes are adequate, but not great for long, steep down hill stretches. Down shifting early really helps. It's possible to upgrade to larger calipers and rotors, but the limiting factor can be the wheels as the larger calipers may not clear the wheel. Upgrading to 17in wheels takes care of that if it's a problem. As for axle and ujoint strength, certainly they aren't as strong as a D60, but so far I have not had any issues, but I drive very easily when in 4wd and crawling over rocks. You should be fine.
Agile Ride improvement package