I've used nickel permatex on all head, rod, and header bolts, and anything from aluminum to stainless with good results. I don't believe it to be any better or worse than aeroshell, it's just something I've used in the past and trust. If it has threads that's what I use
The first time I ever heard anything about 'Aeroshell' was this thread. Never knew about it and still don't know much to it.
I'm still working on the tube of permatex. It's got a couple more years to go.