I migrated from protools, but that was a while ago…
Hmmm, what do I miss… I miss the Nuendo lag! 
Ok, Seriously now. Your usage will vary… I record mostly bands and VO for cable networks.
I still consider myself a novice in relation to my knowledge of PT vs cubase and nuendo since I had not used Pro Tools since version 4 or 5.
I miss having variaudio built in. Melodyne fills the gap here, but costs money.
I miss some of my VST plugins that are not available in rtas so I am waiting for aax to come up before I get my substations.
Nuendo’s automation panel. I used it all the time.
My mackie controllers seemed to work a bit better with nuendo. I had issues with PT at first but it all seems fine now with v10. You should be good though with your Euphonix surface.
There are other things I miss, but it is probably just my lack of knowledge on how to do it in PT. The bottom line for me was I was tired of waiting and tired of being frustrated with Nuendo’s numerous small and some large issues. Nuendo SEEMS more complex and deeper featured than Pro Tools but what Pro Tools does it does very well. I write SEEMS more complex because again, it may be my lack of knowledge of how to do some of the same things in Pro Tools.
Why I now use PT:
My favorite versions of Cubase and Nuendo were version 3 because they just worked great. All my problems started with Cubase 4 that was crash city, so I didn’t bring Nuendo to v4. I skipped it. V5 on the cubase side was good until 5.5 and Nuendo 5 roots came from there so the problems came out of the gate but for whatever reason, it didn’t seem as bad as Cubase 5.5. I am probably hallucinating though because I wanted it to work like I remembered Cubase 5.0. All my 3 Steinberg licenses are held back now. No Cubase 6, no Nuendo 5.5x. It could be that I am a power user with the type of work I do that these things affect me because it is the complex projects that give me grief with current Steinberg DAWs. If I am screwing around doing goofy jingles, things are better.