I spent a lot of time looking at E60 and F10 petrol replacements for my E90. In the end, what put me off was the injector related problems of the N53 engine. I also looked at earlier N52 engined E60s but all were in rag order. I then considered a trip to the UK to buy a F10/F11 535i with the N55. In the end, I gave in to diesel and bought an E53 X5 M57 instead!
If I were to have gone with a diesel F10/F11, I would have stretched to the B47 as reliability seems to be much improved over the N47.