So far I've bought Magma, MB-7 and Metaplugin. Metaplugin just got ported to AAX for PT11 but it has the sample rate issues just like MB-7. This isn't a problem if your sessions are in 44.1 though. Magma on the other hand - although more expensive -doesn't have any sample rate issues (that I've seen) - and on top of this has audiosuite (which is amazing for printing preamps or tape effects). Magma in OS X can't see 64 bit nebula though....
So to summarise, my personal preference when using PT10 running 32bit Nebula, Magma is hands down the best option.
In PT11 the only option at the moment is to run sessions in 44.1khz and use either MB-7 or Metaplugin. Of which I would use Metaplugin because I prefer the interface and the fact the adjusting parameters doesn't cause a CPU overload in Pro Tools.
I bought MAGMA when it was on sale for $99 just to use with Nebula in Pro Tools. I have both Pro Tools 10 and 11, and MAGMA works for me in both. I only work at 44.1 sample rate, so I can't speak to any sample rate issues or not.
Audiosuite is great, I can create presets and just apply those to every track. The only problem I have is most of the time Pro Tools won't shut down correctly and hangs if I have MAGMA as an insert on a track with Nebula. (I'm on Windows 7 64-bit ), but this doesn't seem to be causing any problems.
This is awesome info guys - thanks so much. I guess I'll snag Magma when if it goes on sale. Too bad it's not working with 64 bit Nebula though - (although I haven't upgraded yet as I'm still confused as to the best route).
I'm surprised to hear you guys not working in higher sample rates?