The N54 engine, and every engine that BMW manufactures, is on a level of engineering achievement that is highly, HIGHLY, underrated! The S85 V10 was and is an engine that is on par (if not above) the likes of Ferrari's Best, Lamborghini's Best, and most definitely Porsche's Best.
The S70/2 that was used in the Mclaren F1 is 18 year old detuned F1 technology.
Think about that next time you look under the hood at a 4 yr old S85 in an M6 or an M5. That's 6 yr old detuned F1 technology.
As far as the S65 goes.... it is only similar to the S85's basic design. I can assure you, that its design is superior in every way. Regardless of its lower output.
(Porsche flat 6... hah!)
These engines are able to run at what BMW specs them out at... ALL DAY LONG! Reliably! They have been built to withstand a certain (ridiculous) amount of abuse, and then they turned the dial back, and put them in street cars! lol!!!
Now... I am in no way saying Porsche sucks. But don't put them on such a high pedestal. Their saving grace, is that they have always built a single focused machine. Not an entire group of well rounded individuals. This is what we have all been asking for BMW to build... a single focused machine. No watering it down!
(whew.... I'm done!)