N52 is rated 255hp at the most powerfull version for X5 and 530i station wagon.The "problem" with it is that there is virtually no torque until 3500-4000 rpm,after that it pulls very hard and all the way to 7000 rpm redline.For me it actually feels less "torquey" than M54.
I love this engine in my 530xit,and i am not afraid to rev it when I need that extra power,but it may be too "laggy" for some people's taste.You want to drive one to see if you like it.