Plenty of 700+ N54s out there, N55s have hit 800whp but not as many people have pushed the platform as hard yet. Those motors might eventually run into the same crank hub issues that the S55 is known for, but there aren't as many DCT N5x cars running as high of power as you can get on an S55 with simple hybrids. Then there's the n54 injectors, n54/early n55 hpfp, a million leaky gaskets, etc...
Vargas seems to do ok with their N54 hybrids, but their N55 hybrids are a total joke, they've been on preorder for 3, 4 years now? They had an n55 twin turbo product announcement that went nowhere too. Any time I see the guy he's just starting shit with people and usually ends up looking silly.