Both are pretty good cars... ya.. the XXX-4 is getting old.. I hear everybody say it breaks a lot... well.. they all do when you race modified.. If you don't hit anything.. and land on all four.. there is no problem.
If you make sure to maintain the car, the belt won't blow.. you can tell when they start getting bad.. so change it.. I race mine every weekend.. my belt is 3 or 4 months old..
I think people forget that when you get a new car, everything is new! So of course it's going to drive pretty nice compared to a used car. Also setup is very important. Not every stock setup is going to handle every track or driving style correctly.
I've driven B44 and it's nice.. but its a bit too twichy for my liking in the air. My XXX-4 is a lot more stable in the air. But again that could just be the setup it had or perhaps it didn't agree with my driving style.
Bottom line.. without getting into a flame war.. is that both are very competitive and it's a choice...
Whatever you decide, have fun!
Jerome